I most commonly find it during payment processing and other spots where devs are trying to do fancy input validation or styling in forms, especially on mobile.

I most commonly find it during payment processing and other spots where devs are trying to do fancy input validation or styling in forms, especially on mobile. The most common issue is that the the cursor isn't moved correctly when accounting for automatically inserted spaces or hyphens and it can be pretty much impossible to enter the correct numbers without overwriting previous numbers. Autofill also generally fails in these scenarios.