To the best of our knowledge, there is no connection between the quality of a replacement screen and the Face ID system. There was a short span of time in which Apple was disabling Face ID following a screen replacement on one of the later model phones; I can't remember if it was like a 12 or a 13, but following the (presumed) negative public reaction to that, they later relented and removed the connection between a replacement screen and Face ID.
I'm not aware of that ever having been the case for the XR, so I'm not even sure it was worth mentioning; in the case of the 13 the cure eventually became just a matter of updating to a later version of iOS.
So, outside of that, the leading cause of Face ID issues is damage to the front sensor assembly during the transfer to the new screen. Check the flex cables for any tears or excessive bends, along with the FPC connectors on both the cable and the logic board for bent or broken pins. Also, look at the components mounted next to the FPC connector on the logic board; those occasionally get knocked off and can cause issues as well.
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If you check around you can find instructions for testing the earpiece speaker components individually to see if one of them isn't working. The parts you are concerned with that are tied to Face ID are the ambient light sensor, flood illuminator, and proximity sensor.
To the best of our knowledge, there is no connection between the quality of a replacement screen and the Face ID system. There was a short span of time in which Apple was disabling Face ID following a screen replacement on one of the later model phones; I can't remember if it was like a 12 or a 13, but following the (presumed) negative public reaction to that, they later relented and removed the connection between a replacement screen and Face ID.
I'm not aware of that ever having been the case for the XR, so I'm not even sure it was worth mentioning; in the case of the 13 the cure eventually became just a matter of updating to a later version of iOS.
So, outside of that, the leading cause of Face ID issues is damage to the front sensor assembly during the transfer to the new screen. Check the flex cables for any tears or excessive bends, along with the FPC connectors on both the cable and the logic board for bent or broken pins. Also, look at the components mounted next to the FPC connector on the logic board; those occasionally get knocked off and can cause issues as well.