They're rubbish bins (or perhaps textile recycling bins, but probably not) specifically for national, regional, and/or local flags.
Edited to clarify: No judgment, I am not making a political or societal argument, just posting about a thing I learned exists. If this post gets hijacked I'll ask the mods to lock it.
As a European i would realy like to know what is happening with the Flags after they get thrown in the bin. Like are they getting a burrial, are they just thrown into the real trash, do they get recycelt...
Based on my quick google. I'm guessing they're handling burning them / shredding them.
Thank you