Upgrading between versions might, but that requires you to manually run sysupgrade anyway, at which point you probably should be reading the release notes, which should mention it.
Do you have any examples where it happened without being mentioned in release notes, or without a version bump?
The changes aren't made for the heck of it, they make a more consistent system overall with new knowledge.
No one in the comment chain claimed otherwise. Breaking changes every rand() * (6 months) is not much better than breaking changes every 1 * (6 months). It still means you have to validate your firewall configs once or twice a year and randomly need to push these changes to network appliances with the same cadence. A key benefit of application stability is not having to constantly read release notes and check if your use case is affected by the changes.
> You have six months to make mostly minor changes to pf.conf before you are out of support. They release every six months and patch the last release.
Yes, they have a schedule for rolling out breaking changes. This is a maintenance burden.
> The changes aren't made for the heck of it, they make a more consistent system overall with new knowledge.
The same is true of many breaking changes in applications and APIs broadly. A cleanly designed system does not magically make the ensuing maintenance burden disappear. We probably all agree that OpenBSD and pf are well designed but we should not ignore its costs.