I doubt Apple just learned of the pending EU rule 12 months ago as it was passed.

The alternative is to take a gamble that it won’t be approved and then be stuck with phones that weren’t in compliance (ignoring the 24 month grace period) and having the development clock start immediately for future models. I’m sure they saw which way the winds were blowing, knew they had no populist counter argument opposing the change, and decided it was in their best interest to join literally every other manufacturer on the planet in using a standard port.