You’re a brave man for undertaking a manual, DIY back glass repair!
At any rate, the Front Camera/Sensor Flex shouldn’t be affected by the back glass removal but from a best practices perspective, you should have removed the screen, logic board, battery and NFC charge coil before doing something as destructive as a back glass removal.
Start by carefully inspecting the flex and connector on the logic board. If that looks good, you could try a replacement flex to see if that solves the problem.