Face ID stopped working after screen replacement

Hi I’m an experienced self-taught repair technician and have done numerous repairs but there was an iPhone 11 that I did a screen replacement on before and the Face ID wasn’t blocked. That same customer came back to me to get another screen replacement (with the same phone) a while after and once I did it the phone said “Face ID is not available at this time. Go to settings for more information.” I then put the screen that I took off back on to the phone and the message still remained. I didn’t touch from camera/ Face ID at all and I’m very confused. Since I’ve done iPhone 11 screen replacement’s numerous amount of times and never had this problem. I even updated the phone and it didn’t work. I also transferred the data of the screen. So I don’t know why this occurred.