Apple probably didn't "break" anything in their code; it just sounds like they updated their codebase (e.g. changing APIs, deprecating older approaches, improving various things, etc) to be more efficient and effective. This is a pretty common thing with codebases, including Construct (e.g., moving from Construct 2 to Construct 3).
I think what we are all asking is if the Construct 3 team is doing anything to align with the new iOS 15 coding standards? It may not necessarily be a big thing, might just be a few updates to get it aligned?