A feature of meeseeks-dev, which we use to automate backports, is to create backport PRs based on the milestone rather than on a label (as we're currently doing). This is enabled simply by adding, e.g. on-merge: backport to v7.1.x to the milestone description. This would remove the need for most backport labels (except fo Manual Backport and Still Needs Manual Backport), and simplify developer workflows, removing one opportunity for mistakes in every PR where someone thinks of milestoning to a maintainance branch but forgets to add the corresponding label.
I initially assumed there could be a reason not to use this feature, but after almost 2 years working on astropy, I still haven't found one, so I'd like to propose this change, so if it's rejected I'll at least know why.