I have had a totally different experience. After a few early months in which Asus updated the poor release software very frequently, almost all issues were solved. Everything works quite well now. Although I have quite a few comparable phones (Pixel 5, Pixel 4a, Xperia 5 mk2) that also work well, I keep returning to the Z8, which I clearly use the most.
Almost all problems I had after the update to A12 were in fact solved by a reset.