Only a child or a completely naive idiot would unironically want to get into game testing. That stuff is soul-crushing. Besides, in the "AAA" industry the job is for small subcompanies formed exclusively by the stiffest "office people" stereotypes who hate their jobs, not gamers. While there are a few companies who do test group stuff with actual gamers, that's usually at/past beta stages, and kind of a rarity. Testers literally exist so programmers don't lose billable hours in running what they coded to check if it works or not.
For those of you that code at home, it's outsourcing the process of running your project after building. You can already tell how fun that would turn out when done over and over and over again. You don't even get the respite of having to work in code after a testing session.
For the rest, and with some simplifications: You play specifically tailored and incomplete versions of a game, to test out for things like "does the player character go through the floor when walking?". Then you write a report. Over and over.
This, combined with the disinterest of the office drones, also helps minimizing possible leaks since they don't get access to "the whole" (and NDA contracts are 101% restrictive). But also maximizes the possibility of not finding breaking bugs in the whole package, and that's why so many games come out with completely obvious bugs that aren't caught until after release.
That stuff is so nasty I don't even wish it on a sperg like Lyurong, to be honest.