There are some serious concerns with Firefox's plans to turn in DoH. I, for one, am not happy with all Firefox DNS traffic being sent to a US companies servers. See this article for more info:
IMHO Mozilla and Firefox should be supported by the opensource community as much as possible, by working with them rather than ditching them each time they make a choice that might not be exactly perfect, because I believe they are trying to do the right thing, and we would be much poorer without them.
Fosstodon is an English speaking Mastodon instance that is open to anyone who is interested in technology; particularly free & open source software.