Ah ok will make a backup from my working FP persist img next time when I think about to switch to a custom rom. Back on OOS and FP works like a charm even on the last ota where some users reported that the FP does not work properlyCan't answer that for sure about coming back from custom rom. I haven't flashed anything except Lineage and that was back when my FP was broken. But if you keep the original persist.img you can always reflash in fastbootd to restore if it breaks. I don't think any of the custom roms have FP working because OnePlus has not released the sources yet for any development. The phone is too new.