I somewhat disagree. The best way to protest is to try and get as many people to switch to Lemmy as possible to give this platform the opportunity to take off.
If you have a favourite niche community, create a Lemmy page for it and see if you can get the mods of the sub to advertise it or put it in the sidebar at least.
It’s going to be a bit of a ghost town at the start here until we can get some user growth and those niche pages are huge for it.