userofgos how did you even downgrade to the previous version? From my understanding downgrade protection prevents this.
Downgrading involves unlocking the bootloader and flashing both boot slots with the version you want to downgrade to, then relocking the bootloader once you're done (i.e. what you did when originally setting up GrapheneOS on your device, assuming you didn't buy it with GrapheneOS pre-installed). The only Android versions you truly can't downgrade to are those with outdated bootloaders that have a lower anti-rollback value than the current one installed on your device. The most recent Android release that incremented the anti-rollback value was the May 2025 security update on both stock Android 15 and 16 (unsure of GrapheneOS equivalent), so going from Android 16 QPR1 to the last Android 16 non-QPR1 release is no problem.
To actually downgrade, you just obtain the factory image of the release you want to install (I did this by copying the latest download link for my device and replacing the version number with 2025110801, the last non-QPR1 release with security preview patches), and follow the command-line install guide to actually install it. This will wipe your phone, similar to when you first installed GrapheneOS, so make sure you back up your data first (as mentioned before, Seedvault apparently works, but I wouldn't rely solely on it).
Finally, should you choose to go this route, keep in mind that it will reduce your phone's security as more updates get released. And if Google decides to do more anti-competitive Play Store practices (like the Play Protect thing a few months back that stopped a bunch of apps from opening if not installed by Play Store), they won't be fixed until you update.
userofgos Did you create your own build with they old ui added back in?
If only it were that easy for me to do, but 1. AOSP is a very large project spanning hundreds of repositories, and so I haven't found which aspects of the UI I would need to revert, 2. on that point, I don't have >300GB of space lying around (except on very slow HDDs) to save the entire AOSP/GrapheneOS source code (contributing to the first problem, because the AOSP repository browser kind of sucks), 3. My computer only has 1/4 of the RAM needed to successfully compile Android, and 4. I don't feel like I could commit to keeping the reverted UI up to date, at least not without help. Oh, and I feel like I'd run into coding skill issues (no pun intended) very quickly, as I've never worked on any OS before. I would be interested to see if anyone else cares enough to maintain an up-to-date, pre-M3E variant of GrapheneOS, though.