PS4 Fat gets too loud even after thermal paste and cleaning

Last week I decided to change my original PS4's thermal paste and give it a good cleaning because after 6 months it was the fan was starting to get loud.

I throughly cleaned almost every part even the fan and heatsink and then I applied new thermal paste and thermal pads.

I was confused when the fan was still as loud as before and I decided to open it up again and check if I misplaced a thermal pad or something. Nothing was out of place so I guessed maybe it was the thermal paste application. I switched from the X pattern to spreading the paste (I used Arctic MX-4 because I ran out of NT-H2).

After reassembly, I tested again and the fan would start low then after 5 minutes would get loud again until I closed the game I was playing. Before, when I closed a game, the fan would be still running and slowly get quieter as the system cooled down, but now it almost immediately slows down after I quit the game.

I don't know if this is a fan problem, a thermal paste problem or something else.