I've actually just had my eSIM decision backfire on me.

I switched months ago and hadn't had an issue until I got ready to go to an airport last week. I figured I'd be able to switch off the eSIM and switch on Airplane Mode so my phone could essentially be an offline iPod, but when I landed and tried turning it back on it didn't work. I then found people discussing the same issue on their phones (GrapheneOS + Pixel 7) and really regretted messing with it.

My carrier's account login hilariously requires an SMS 2FA to the phone number that's been yeeted from existence and since I've been staying with in-laws this Christmas I'm not willing to sit on hold for however many hours to recover my account till I get home.