Workaround for "Backup Not Encrypted" notification on Time Machine

So I made the giant leap from a 2009 iMac to a 2020 (Intel) only to discover the "joy" of a T2 security chip.

I know how to disable to the T2 chip temporarily but is there any way to keep it off until I reenable it?

I'd rather use Time Machine like it's pre-T2 given what I know about Apple Silicone replacing Intel, how iCloud eventually becomes unreachable on very old versions of macOS (not working so great in Snow Leopard anymore!), that Apple's signed certificates expire, making reinstalling the original macOS on a "vintage" Mac a royal pain, that Internet Recovery can fail on the same grounds (Apple server may still be online but older versions of macOS can't install without setting back the date/time to when the certificate is still valid), how difficult it will eventually become to find working links to the full macOS installer that shipped with a given Mac, etc., etc.

Now for a caveat: For mobile users and those in enterprise situations by all means take advantage of end-to-end encryption, FileVault and the like.

For me, I want backups from my iMac to my external drive to remain as "future proof" as possible (meaning unencrypted). To that end, I view Apple's changing security measures to be among the top threats to accessing my own legacy macOS and "orphaned hardware" content some 5-10 years from now, hence I would like TM to function like it did prior to the T2 chip encrypting the entire HD.

Is this doable?

If not, how do I turn off the "Backup Not Encrypted" notice that reads "Time Machine is backing up an encrypted disk to an unencrypted disk". I checked in "Notifications" but don't see a place to turn it off.

Thanks.