Three keys on my keyboard start acting strange when I play games. Why

I was playing a game three days ago and suddenly my S,X,Z started lagging and then stopped working. After closing the game and restarting my computer they were okay.

Everything works nice until I start a game and play for around 10 minutes, then my S key starts lagging to a point where it stops working aswell as X,Z. When this starts happening I have tested several things that occur:

1. When I press all 3 keys S,Z,X in a notepad it starts spamming all 3 keys constantly like "sxzsxzsxzsxz", usually it should deliver this kind of input: "xzsssssssssssssss".
2. Pressing S or any of the other keys once sometimes results in a double and even triple output.
3. Another thing is that if I hold the 'D' key for example and let it spam for 2 seconds and then press 'S' it does not cancel the D's being spammed, if it works okay it should stop the D letter spam like this “ddddddddddddds”.

The thing thats stopping me from buying a new keyboard is that it costs like 100 pounds and if I'm not playing games the three keys are working perfectly fine. I think that if it was a keyboard issue the keys wouldn’t work at all.

Does anyone have an idea where the issue might be coming from? The game I played when it happened was Valorant.

PS: I've reinstalled windows & reseated the RAM, but it didn't fix the issue.