There are lots of good alternatives, just nothing that mirrors Stack Overflow's goal exactly. Lemmy instances, subreddits, forums like code ranch, platforms like dev.to, etc.

It needs more traffic (and that'll require better servers and more moderation with training to make sure that it doesn't follow the same arc) to become a standard place to go, but I've become fond of Codidact. If I remember correctly, the founder left Stack during one of their bigger moderation blow-ups.