Phone unlocking itself

I have the iPhone XR meaning it has Face ID but yesterday and today my phone kept on unlocking itself without me needing to put the password. Usually this is normal if I have my mask off or just have my Apple Watch with me but my Apple Watch was dead and wasn’t with me and I had my mask on also u have the attention option on too. I changed my password for a personal reason and since I was so used to that password I sometimes was putting in that password instead of that actual one but like not even 10 minutes ago I was typing in that password (the old one) with my mask ON and it automatically unlocked before I got to finish typing in the password. Does anyone know how to fix this?