Now that's IMHO quite bad. If you ever want to move your repository to
another provider, you're losing precious information of the history. Thus
everything related to the description of a commit should ultimately go into
the commit description, not (only) into the PR description.
An opposite example is that if you're tracking commit IDs in PRs/issues (i.e. the description is referring to a certain ID) and you rebase your stuff for some reason, all of your public information becomes invalid. You can fix such things easily with a script in commit messages but only manually in PRs/issues.