That's pretty old practice, for example, "anti-war" rallies generally attract every nutty "left" group and they all have to agree on everything for "solidarity" purposes. There was a great website back during the Iraq War protests that would compile all the crazy signs and groups completely unassociated with the Iraq War at these. Climate change was one of the major things that displaced the Communists from positions of prominence at anti-war/anti-Israel/etc. protests.
edit: Google wasn't entirely much help at this due to its increasing desire to strike words from inquires and only search recent pages but I managed to find it and it's somehow still up: https://www.zombietime.com/
edit: Google wasn't entirely much help at this due to its increasing desire to strike words from inquires and only search recent pages but I managed to find it and it's somehow still up: https://www.zombietime.com/