Is this one of the repos that uses Gerrit? Does JJ play well with Gerrit?
IIRC Gerrit was super picky about amending commits and I was worried JJ's laissez faire attitude about creating git commits on demand wouldn't jive well.
There was a PR for a `jj gerrit` command, but at this point, it's not super needed. Here's the main bug tracking this https://github.com/jj-vcs/jj/issues/4387
Beyond that, the jj, gerrit, and git butler folks are working together on standardizing the change ID concept so they all work well together without extra tooling. That's going to take a long time though. Think "store the change ID in the commit rather than as a trailer", that kind of thing.
JJ does create commits without you explicitly asking but you do still have direct and fine grained control over it. It's not magic it's just that it's occasionally implicit. And squashing and splitting is nice and easy.