The bigger issues for me are it makes history impossible to read (every change is hidden in an avalanche of crap), merges are a mess (you definitely want to spend forever merging autogened files, right?), PR reviews are annoying, etc.

Depends how much generated stuff is there. We have our graphql schema in git even though its auto generated via a library. But its useful in PRs to see exactly how the schema changed as a result of the root change.

Yeah if there's not a lot of it, and if it's easy to regenerate, it can be fine.

You may want to set the '-diff' attribute for these files so that git will not show diffs for these, instead it will show 'Binary files differ'.

There is also '-merge', which will cause git to not attempt to merge the contents, but just ask you to pick a side.

The challenge however is then verifying the contents of these files in things like merge requests.

See https://gitirc.eu/gitattributes.html