OTA Updates stuck on TWRP Bootloop

[nullscm]

I downloaded the OTA Update with the integrated downloader and now my device is stuck in a bootloop, boots to TWRP everytime, even after manually flashing the new system image via fastboot.

I know it's my own stupidity to think that OTA Update should work with a custom recovery :D

Is there somehow the possibility to delete the downloaded OTA Update or revert the Update flag that the Phone could boot normally to the system again?

Like pm.dexopt.boot-after-ota or sth?

Thanks for you work :)