Hi Interista,
What Avast version are you running? If you disable Avast Passwords extension in Chrome (via Settings -> More Tools -> Extensions, there should be a slider for disabling), does autofilling still happen?
I'm asking this because the same code is used to get CC data from vault to Avast UI as it used when getting it for the extension for autofill. Fact that you have no CCs stored in Avast Passwords according to Avast UI, leads me to believe that you have your CC saved in either Chrome or some other program for managing CCs that has its own extension in Chrome.
Dan