Yeah, no surprise that a bunch of groups are not responding well to MD throwing them under the bus to try and cover their own ass.
I mean, it's not like either of them are really blameless, specially MangaDex that's trying to be "a more 'neutral' middle man to access manga" or whatever you want to call them, by trying to neither be bought or put ads to fund themselves and trying to push the most legal face of the scanlation scene as they can. They did just provide a ground for anybody to upload, with just the statement on their desire to shape the site to a certain degree, but without really having a way to enforce it. One could call it maliciously trying to obtain a wider user base for their site by hosting works that they don't agree with...if only there was anything for them to gain except MORE problems (as the occasional instability of it demonstrates), since, again, they don't profit from the site anyways, beyond whatever they crowdfund for server hosting costs.
A lot of groups obviously aren't being particularly legal, not even because of translating content for mass consumption at no obvious monetary benefit to any of the people making the original work, but more because of doing that WHILE profiting out of the work (regardless of justification, legally it isn't something they have sufficient justification to do). But it still feels frustrating to just dump their entire work, sweat and sometimes tears into a work, upload it to a particular platform hoping it would remain for some kind of posterity, and then all of a sudden having it vanish.
Frustrating overall, yet I can still see the why for both sides of the equation. No shame to either side in particular, just a shame that the wider scanlation scene can never agree (or really accept) these kinds of platform that try going for legality.
After all, we aren't all here because we necessarily can afford to just spend money buying any and all works whose cover looks interesting or that is being talked in particularly good light in forums and the like, and not all official works have the kind of special touch that particular groups give to the TLs they work on, be it care in conveying the original nuance more than trying to make it palatable to a foreign audience, or in trying to do something fun to make the work more charming without fully misrepresenting it (shark isekai my beloved, how much I miss you).