Mozilla is unhappy because the use of browser engines other than WebKit will be restricted to the EU, forcing them to develop two different apps.
For an independent browser like Firefox, managing two browsers is not easy, so it can be forgiven that this could be seen as almost harassment.
Also, the fact that the use of browser engines other than WebKit is limited to iOS means that the use of WebKit is still forced on iPadOS, which also increases the effort for Mozilla.
Why would you want to do that?
Genuine question.
Because if it is the hardware you want to keep and not the software, there are good android based options. And if what you want is control over the software, there are also good android options. I’d recommend a Pixel phone, and you’ll always have the option to de-goggle it completely with either CalyxOs, GrapheneOs or similar ones.
I was more poking fun at how ios users who let an ultra mega corp holds all their data and actively cripples privacy efforts while touting a false sense of privacy as marketing, never ask to de-apple their iPhones