Credit where credit's due, Chibnall has a masterful ability to make an episode with a show-changing lore reveal, Cybermen, the Master, Cyber-converted Time Lords and ruddy Morbius Doctors into something egregiously mundane. The 'big lore reveal' isn't offensive because of what it does to canon (mostly), it's offensive because it is wholly meaningless.
For weeks we've been promised that 'Everything you know is a lie' and 'Everything is about to change', but the problem is what that translates to is 'Everything is about to change (for you the audience)' rather than 'Everything is about to change (for the Doctor)'. Because evidently the Doctor couldn't care less. And, yes, it was never going to irrevocably change her character, but that then begs the question; what was the point? Why did we spend a season teasing this, and have an hour's worth of info dump if it is wholly meaningless? The best I can come up with is 'because it will get headlines and shock fans' and that is just the absolute worst way to write any show ever (looking at you GoT).
Even worse than that, in order to get to this point you had to literally incapacitate the Doctor and make her wholly ineffective and have the companions do barely anything of consequence so as not to detract from the main event. It literally feels like someone writing stuff they've had in their head since being a teenage fan, and just splurging it out on the page with no relation to anything else.