The OnePlus 8T will be superseded by the new flagship 9 series soon; however, its new official public Android betas might help keep it relevant for some time to come. The latest one contains a bunch of bug-fixes, and also upgrades the phone's security patch level to March 2021. It also adds one or two features, including a time-stamp for the stock camera app.
https://www.notebookcheck.net/The-OnePlus-8T-s-OxygenOS-Open-Beta-2-update-contains-the-March-2021-security-patch.528825.0.html