Keyboard problem typing random numbers

I am running on a MacBook Air (early 2015) with MacOS Catalina.

Anytime I type in any of the ASDFGHJKL keys, the computer automatically types in a1s2d3f4g5h6j7k8l9.

It also happens when typing in any number.

This does not happen with any of the QWERTYUIOP or ZXCVBNM keys.

I already tried resetting the SMC once and the problem was immediately solved, but two days later the problem came back and that solution didn't work anymore. I also tried with the PRAM but it just didn't work. Sticky and slow keys are off.

The problem is not present when using an external keyboard.

My input source is Spanish- ISO.

This is the fist time in 4 years+ that i've encountered this kind of problem.

IMPORTANT: I had my computer downgraded to Mojave by authorized technicians because of a storage problem I was running into and that was when I first encountered this keyboard issue, I then decided updating to Catalina to see if the problem fixed itself, but it didn't.