Is there any reason to suspect EFF believes stallman was not right? I remember they opposed his reelection to FSF in 2021, but that was about his alleged misconduct, not his views on software (in fact they said they believe in FAF mission importance)
Nah, just gossip. I remember an interview with Linus Torvals where he expressed that he thought that some elements at FSF were sleezy (he didn't say or insinuate Stallman) or maybe dishonest, I don't remember exactly, due to GPLv3. He said "I understand what they're trying to do, but it should be a different license, not a new version of the same license". And then he finished with the comment "If you want to support I'd send my money to the EFF instead if I were you", which gave me the impression that there was some tension between the EFF and the FSF. That's it.
But Stallman WAS right about basically everything though.