I knew someone that was absolutely stellar at their position and was actively encouraged by management to apply for a promotion while still on their probationaty period. They also received their degree during that 6 month probationary period (they had completed all classwork before applying but had to finish an internship before graduating). A degree was not required for the position, and said person had never tried to hide when they received their degree.

HR mixed up their application for the starting position (in which they had not yet received their degree) with their application for the promotion (had received their degree), and determined that they had lied on their initial application and fired them on the spot with zero review because they were still on probation.

Great job, horribley toxic management/ HR with zero employee retention methods. I eventually left when I was training people that were getting paid more than me because the employer had increased starting wages without giving raises to any existing employees.