I was reading this the other day when I came across this feature because I’m stacking PRs recently which I don’t usually do

https://andrewlock.net/working-with-stacked-branches-in-git-...

Another commenter posted this link which was a bit more succinct

https://blog.hot-coffee.dev/en/blog/git_update_refs/

There isn’t much to it though, you just go to the branch and run git rebase with the update refs flag.