It's generally fine if you force push a branch that you're the only one working on. In many projects, there's an expectation that the 'PR Branch' you create in order to make a github pull request is owned by you, and can be rebased/edited/force-pushed at will. It's very common to do things like `git commit --amend --no-edit` to fix a typo or lint issue and then force push to update the last commit.

This has it's problems, and there's a reason things like Geritt are popular in some more sophisticated shops, as they make it much easier to review changes to PRs in response to reviews, as an example.