These actions can be classed as slacktivism and as impotent virtue-signaling, sure, but I believe that the actors of these methods of protest are trying to do what the left calls "creating safe spaces" and genuinely feel that they are "showing their support" and therefore somehow...helping.
The thing is, they may be achieving that first part - creating a safe space, perhaps unwittingly marginalising, demonising, and isolating the very people who can affect the most change (i.e. politicians, policemen, russian people, going by the examples of causes in OP's post alone), at a further cost of inconveniencing absolutely everyone - testing the resolve of existing allies, and likely creating new opponents out of those who were on the fence or apathetic.
It's basically taking the "Thoughts and prayers" under a Facebook post to the next level.
It would be fine if the banner was close-able or displayed once a day or something along the lines of that. The problem isn't that they're showing support. It's doing it a completely obnoxious way that's the issue.
If you are one of the people doing this, look around you. Literally everyone slapped a BLM banner on their website, when everyone has done that yours literally adds nothing. Sure, put that message up there, but make it close-able. Not something that takes up valuable screen real-estate permanently.
