I tried putting a diamond sticker on Wagyu but it keeps rotating when I save and exit. I tried a Slay sticker and that also rotated. I tried putting a sticker on Wagyu's body and leg and seems it kept the rotation there.
Seems it shifts the rotation a bit, so I can rotate it at a different angle before saving (screenshot 1) and it'll rotate to the angle I want (screenshot 2). Workaround for now.

I closed the game but Steam didn't download any updates. So I verified it 30 minutes ago and still does it.