Masking seems inconsistent

Depending on fast or slow you type in your credit card number, if you have masking turned on, sometimes it will show the last four digits, sometimes the last three. If you type in the numbers really fast, it will mask all the numbers.

What is the expected behavior and will we be able to select how many of the numbers get masked?

No file, test, or entry point is named. First reproduce the masking behavior with slow and fast typing while masking is enabled, then trace the masking implementation and establish the expected visible-digit behavior and whether configurable masking is in scope.

Written by the indexing model from the issue text.