It's a bit more widespread than that given the bug(s) in the stack affect it's own firewall as well as other related networking apps like VPN software.
It's still, allegedly, borked in the 15.1 beta but Apple have now acknowledged (to beta testers) this isn't intentional so that's at least something but let's be honest, Apple shouldn't have released it like this especially as it's now transpiring they were already aware of the issues during beta testing.
Apple's QA of releases has been pee poor for a while but i think a lot of this stems from Apple's current, imo, daft mindset of having to have a yearly major release which seems to be resulting in their developers rushing and failing, two years in a row i believe, to add headline features in with the initial release whilst letting reasonably sized bugs through.
I think they would do a lot better if they went back to the early OSX era of having a major released every few years or whenever it was ready.