iCloud Reminders DIFFERENT on two devices with same Apple ID

I have several devices all using the same Apple ID. If I go to iCloud.com/reminders and login, I will see the "correct" set of Reminder Lists with all the correct Reminder Items in those lists. If I look at Reminders on my laptop, I also see the correct set. If I look at Reminders on my iPhone 14 pro max or iPad or an older iPhone 11, I get the "wrong" set of Reminder Lists with wrong/very old reminders in them.

Remember several years ago when Apple started adding features to Reminders like being reminded when messaging someone, and such? You had to elect to migrate your cloud-based Reminders to the new features and only devices running a new version of MacOS or iOS would be able to work with them going forward. A Yellow Warning triangle⚠️ was applied to each Reminders list on old devices as well as some sort of Reminder Item added to each List that made it clear the cloud Reminders list was migrated, if I remember correctly.

Several months ago, I did two things that I'm concerned triggered the problem.

(1) I turned on a rather old laptop which had not had its Reminders upgraded when Apple started adding features to Reminders many years ago. I believe this laptop had the old Reminders warnings when I first turned it on (and of course a bunch of notifications related to the Reminders went off).

(2) I'm a family organizer and my kids were having issues purchasing items from the App Store and we couldn't verify my credit card. As part of trying to get that fixed, I logged out of my Apple ID on my iPhone 14 and when I logged back in, I think the Reminders were broken at that time although I didn't immediately notice.

To confirm, I'm 100% certain all devices are using the same AppleID and are fully logged in (i.e. no complaints in Settings). In fact, iCloud Notes work just fine between all devices. They all have the latest version of OS, all have Contacts, Reminders, Notes, etc. turned on to sync. Date & time are correct. I've done pretty much everything I (or Apple Support) can think of with no luck. I've force quit, signed out of iCloud, upgraded OS over the months as they've come out, even did the firmware reset of my iPhone via the laptop. I've removed old devices from my account and Apple Support had me install device profiles and screen share both iPhones (when only one was connected to the "wrong" Reminders) so I could gather logs and compare, etc. All with no luck.

My theory is that from some moment in time forward, every new device I activate and connect to iCloud Reminders is getting pointed to the OLD Reminders in iCloud rather than the new Reminders with upgraded capabilities. For example, on affected devices, I can't create a reminder and ask to be reminded when messaging someone (or tag the reminder, etc).

Apple Engineering has been slow (going on 3 months) to get back with me/Support, so I thought I'd seek the wisdom of the community, which I probably should have done in the first place. Any help would be greatly appreciated!