like github is so PR-centric that the entire UX is designed around the assumption that a PR is an indivisible change that will be squashed upon merging (even if creating a merge commit is still the default)
and at the same time it has absolutely no way to link multiple PRs as closely-related changes

now obviously the correct workflow is hidden in there, and it kinda works
you CAN post review comments commit by commit, but some features (such as suggesting changes) simply don't work, and those comments are marked as "outdated"

heck for the longest time, force-pushing a PR was lossy (you lost all previous context)
now it actually logs force-pushes with the old and the new branch heads, but the "compare" button is still completely worthless in case of a rebase...