Ukraine

Here’s a somewhat relevant parable about how hard it can be to destroy a bridge during war.

Another two famous incidents:

The Battle of Sedan

At the opening of the Battle of France, German forces unexpectedly moved through the Ardennes and crossed the Meuse River. Containing the breakout would best be done by destroying the bridges captured. The Germans put up heavy air defense, and both the French and British air forces were unable to bring down the bridges. This was a strategically-critical battle that may have determined the fate of France in World War II.

https://en.wikipedia.org/wiki/Battle_of_Sedan_(1940)

In the central sector, at Gaulier, the Germans began moving 3.7 cm Pak 36 light infantry field artillery across the Meuse to provide support to infantry across the river. By 01:00 on 14 May, a pontoon bridge had been erected over which Sd.Kfz. 222, Sd.Kfz. 232 and Sd.Kfz. 264 armoured cars began to dismount in the bridgeheads. French reports spoke of German tanks crossing the bridges. Such reports were in error, as the first Panzers only crossed at 07:20 on 14 May. Prior to this, masses of lorries, armoured cars and other traffic had passed through, but not tanks.[53]

The capture of Sedan and the expansion of the bridgeheads alarmed the French who called for a total effort against the bridgeheads at Sedan, to isolate the three Panzer Divisions. General Gaston-Henri Billotte, commander of the First French Army Group, whose right flank pivoted on Sedan, urged that the bridges across the Meuse be destroyed by air attack, convinced that "over them will pass either victory or defeat!".[46][53] General Marcel Têtu, commander of the Allied Tactical Air Forces ordered: "Concentrate everything on Sedan. Priority between Sedan and Houx is at 1,000,000 to 1".[4]

No. 103 Squadron and No. 150 Squadron RAF of the RAF Advanced Air Striking Force (AASF) flew 10 sorties against the targets in the early morning. In the process they suffered only one loss in a forced landing. Between 15:00–16:00, 71 RAF bombers took off escorted by Allied fighters. The impressive escort was offset by the presence of German fighter units that outnumbered the Allied escort fighters by 3:1.[60] No. 71 Wing RAF lost 10 Fairey Battles and five Bristol Blenheims. No. 75 Wing RAF lost 14–18 Battles and No. 76 Wing RAF lost 11 Battles.[60] Out of 71 bombers dispatched, 40–44 bombers were lost, meaning a loss rate of 56–62 percent.[60] The AASF lost a further five Hawker Hurricanes.[60] The AASF flew 81 sorties and lost 52 percent of its strength. No 2 Group RAF also contributed with 28 sorties.[61] The bombing results were poor, with three bridges damaged and one possibly destroyed.[60]

Another bridge that also famously held up to a lot of attacks in WW2, this at the end of the war:

The Battle of Remagen

https://en.wikipedia.org/wiki/Battle_of_Remagen

After capturing the Siegfried Line, the 9th Armored Division of the U.S. First Army had advanced unexpectedly quickly towards the Rhine. They were very surprised to see one of the last bridges across the Rhine still standing.[5]: 263–264  The Germans had wired the bridge with about 2,800 kilograms (6,200 lb) of demolition charges. When they tried to blow it up, only a portion of the explosives detonated. U.S. forces captured the bridge and rapidly expanded their first bridgehead across the Rhine, two weeks before Field Marshal Bernard Montgomery's meticulously planned Operation Plunder. The U.S. Army's actions prevented the Germans from regrouping east of the Rhine and consolidating their positions.

The battle for control of the Ludendorff Bridge saw both the American and German forces employ new weapons and tactics in combat for the first time. Over the next 10 days, after the bridge's capture on 7 March 1945 and until its failure on 17 March, the Germans used virtually every weapon at their disposal to try to destroy it. This included infantry and armor, howitzers, mortars, floating mines, mined boats, a railroad gun, V-2 rockets, and the 600 mm Karl-Gerät super-heavy mortar. They also attacked the bridge using the newly developed Arado Ar 234B-2 turbojet bombers. To protect the bridge against aircraft, the Americans positioned the largest concentration of anti-aircraft weapons during World War II[6]: 189  leading to "the greatest antiaircraft artillery battles in American history". The Americans counted 367 different German Luftwaffe aircraft attacking the bridge over the next 10 days. The Americans claimed to have shot down nearly 30 percent of the aircraft dispatched against them. The German air offensive failed.[7][8]

On 14 March, German Reich Chancellor Adolf Hitler ordered Schutzstaffel (SS) General Hans Kammler to fire V2 rockets to destroy the bridge. This marked the first time the missiles had been used against a tactical objective and the only time they were fired on a German target. The 11 missiles launched killed six Americans and a number of German citizens in nearby towns, but none landed closer than some 500 metres (1⁄4 mi) from the bridge.[2] When the Germans sent a squad of seven navy demolition swimmers wearing Italian underwater-breathing apparatus, the Americans were ready. For the first time in combat, they had deployed the top-secret Canal Defence Lights[9][10]: 410  which successfully detected the frogmen in the dark, who were all killed or captured.[11]

The sudden capture of a bridge across the Rhine was front-page news in American newspapers. The unexpected availability of a bridgehead on the eastern side of the Rhine more than two weeks in advance of Operation Plunder allowed Allied high commander Dwight Eisenhower to alter his plans to end the war. The Allies were able to rapidly transport five divisions across the Rhine into the Ruhr, Germany's industrial heartland. The bridge had endured months of aircraft bombing, direct artillery hits, near misses, and deliberate demolition attempts. It finally collapsed at 3:00 pm on 17 March, killing 33 American engineers and wounding 63. But by then U.S. Army combat engineers had finished building a M1940 aluminum-alloy treadway bridge and a M1938 pontoon bridge followed by a Bailey bridge across the Rhine. Over 125,000 troops established a bridgehead of six divisions, with accompanying tanks, artillery pieces, and trucks, across the Rhine.[12] The Americans broke out of the bridgehead on 25 March 1945, 18 days after the bridge was captured.

Air defenses and air-to-surface delivery mechanisms have changed since then, but bridges can still hold up to a lot.

For sure.. but limiting the use case to for example exclude 40tons or armor is already something.

It not really important though, I was just thinking out loud and am sure the Ukranians do the same.. or have even tested it already.

If it was good and practical we would most likely already see it done. Like the new dragon's breath drones.