I don't find myself that bothered by the change, I understand Shrek's appeal and I really enjoyed the old ones and the new Puss in Boots too, don't get me wrong. But his new design, contextually speaking, makes sense to me, he looks older, as does Fiona and Donkey (look at that chin hair). Given that this is clearly some time after Shrek Forever After (child is grown up), him looking like that makes sense to me.
I dunno, maybe because I see it less as an artstyle change, and more an age-up? I wouldn't personally class this anywhere near as bad as the original movie Sonic design, that's for sure (though ngl I would've watched that anyways just out of morbid curioisity).