Never buy a OnePlus phone ever again. They now have a hardware anti-rollback fuse that blows if you revert to an earlier version or install a custom ROM.

https://consumerrights.wiki/w/Oneplus_phone_update_introduces_hardware_anti-rollback

Oneplus phone update introduces hardware anti-rollback

Consumer Rights Wiki
@davidgerard My phones over the last 6 years have been Oneplus. Looks like I'll have to start saving for a FOSS one when it's replacement time. :/