There are surely more options than causing burnout and encouraging everyone regardless of what they're doing. If someone creates yet another veganism organization with conditions conducive to abuse and oppression, obviously they should be criticized regardless of whether they ask for it or whatever. Like if someone is stomping on someone else, it makes no sense to let them because they don't consent to you stopping them.
Be supportive, yes. Show solidarity, yes. But never if it is only reinforcing and instantiating dominance structures.
It's hard to say much more without a concrete example of what you mean, but there are surely ways to be supportive of your peers without uncritically supporting literally anything they do. Sometimes you need to let a friend know they're doing something fucked up and they need to cut it out. At some point you have to look at the fact that every Food not Bombs chapter is run by abusers and think, maybe aversion to criticism makes like no sense. Not to mention that many of the things you should criticize and resist would themselves cause burnout for more vulnerable activists if they aren't.