ARM isn't the problem. Some games have native ARM ports, and x86 games can be run by Rosetta. It's not as fast as native, but broadly comparable with the performance of the previous gen Intel chips they replaced.
A bigger problem on macOS is that they dropped support for 32-bit software a few years ago in Catalina. Not a problem with newer games, but it decimated Mac users' Steam libraries.
And the biggest problem is that Apple just doesn't give a shit about gaming. Every few years, they claim they're going to do games, but quickly forget about it. They've never put decent video cards in Macs, and never hesitate to throttle hardware if proper cooling would mean a larger enclosure, so AAA games typically arrive on macOS years late, when second-rate or integrated video cards can run them.
If they actually cared, they'd have their own Vulcan implementation. Instead, they're focused on their own proprietary Metal API.
Basically, Apple and AAA game studios have been ignoring each other for decades.
Doesn't matter, tbh. The entire problem of giving governments (or whoever) a backdoor is that there's no way to make it only available to the "good guys".
If Apple and co did put in backdoors to satisfy the Brits, the first thing every other government on earth would do is legislate itself access to the backdoor.
With or without a proper backdoor, this law breaks the tech.