In codebases where PRs are squashed on merge, the commit messages on the main branch end up being the PR body description text, and that's actually reviewed so tends to be much better I find.
I understand this isn't inline with traditional git scm, but it's a very powerful workflow if you are OK with some hybridization.
One minor nuisance that can come up with GitHub in particular when using a short reference like #123 is that that link breaks if the repo is forked or merged into something else. For that reason, I try to give full-url references at least when I'm manually inserting them, and I wish GitHub would do the same. Or perhaps add some hidden metadata to the merge commit saying "hey btw that #123 refers to <https://github.com/fancy-org/omg-project/issues/123>"
Yeah I usually default to just a straight up link or a markdown link. Mostly because I usually don’t know the exact number of a PR/ticket/issue - so it’s easy to just copy the URL once I’ve found it.
The gold standard is rebased linear unsquashed history with literary commits, but I'll take merged and squashed PR commits with sensible commit messages without complaint.