I've never watched unknown side effects specifically but it looks like similar vibes to Carol at the end of the world which made me cry about as much as midnight gospel could. superjail has always reminded me of the whacked out vibes of Pendleton ward's stuff, animation is cool, just a bit raunchy and out there - still a cult classic and you can have fun with it. I think the closest thing I can recommend that I've watched is smiling friends - again a bit more raunchy sometimes but not as bad as superjail and gets less deep than midnight gospel. just really dumb fun. If you like smiling friends maybe yolo: crystal fantasy but I didn't watch a lot of that just remember thinking the pilot was pretty fun.
also obviously I could say some studio ghibli, especially howls moving castle, but stylistically/tone wise I know it's different. but it definitely reminds me of the vibe of Pendleton wards work just a little differently, a great chill movie though
also if you've never watched regular show, do that