It’s a shared account to my knowledge. No they’re not going to staff it with their most experienced developers all the time. They may have used it in the past when available. I don’t really know.
It also varies depending on the size of the company. Some companies which are smaller, are likely developers. It doesn’t really matter though just judge based on what you see in their posts.
Nothing specific, beyond “it doesn’t happen with pf, but it happens with Network Extensions”. Nobody managed to dig up that Apple technical notice (TN3165) which actually points out very clearly pf is deprecated with wording like:
It is not considered API. Do not use Packet Filter in a software product that you distribute to a wide audience. If you’re currently shipping software that relies on Packet Filter, plan to migrate to Network Extension.
(emphasis added) Is Proton expected to disregard Apple’s advice? What I would really like to know is why this happens, because it most certainly will be something that crops up with other VPN providers when they make the change.
Perhaps so, and maybe the reason is some sort of Apple issue, but to know really who is to blame someone has to do it. I do know that Proton does have an internal bug tracking system (their developers sometimes mention it on github), so maybe there is a specific reason this thing happens.