The WaitList.dat file can be found as a part of the Input Personalization system that adapts the writing gestures to a formatted text for the user, based on the user’s usage.

I've checked my PC and found I do indeed have a WaitList.dat file that weighs in at 1.29MB. ... Unless it's not on windows 10 pro I don't see the file either and I have written input enabled ...

Two SAP GUI vulnerabilities have been identified exposing sensitive data due to weak encryption in input history features ...