Question Games start to go super laggy after a while of playing on Laptop

[JoanOnFire]

I don't play really heavy games, they used to run fine for most of my computer life (around 2/2 and a half years), but like 6-7 months ago it started to go really laggy, which made me stop playing on my pc for a while.

I've got back into my 'gaming' and took the laptop to an expert who changed the hard disk and put in a brand new SSD, except that he said there aren't any other problems, he also did a whole clean-up of the components (So, I assume it's not a fan/overheating issue).
With the new SSD, I can play the games smoothly for a bit and then they suddenly go super laggy.

I've tried everything I could find and I suppose it's not even the thermal throttling that's causing this issue.
Checked if it was a page file problem and nothing, also the intel thing you have to change from the registry and still nothing.
Also, I have all the latest driver versions.

What else could be causing the games to go suddenly extremely bad?

My specs:

Lenovo V15-IIL 82C5

CPU: Intel(R) Core(TM) i5-1035G1
Ram: 12 GB
GPU: Intel(R) UHD Graphics

I'm not sure what other things I should put here, If I missed anything please tell me.

 

[rgd1101]

what the ssd? how full it is?
cpu/gpu temp and usage during the game?

 

[JoanOnFire]

what the ssd? how full it is?
cpu/gpu temp and usage during the game?

Out of 222 GB, 80 GB are free.
The game uses around 30-40% of the CPU(It goes from 60 to 70 in total) and 900 Mbs on the memory, plus 0.1% in the Disk.
I'm not sure how to check what SSD I've got?