PS4 Pro - Fan goes extremely loud, but air is not hot - I've tried everything

I've got a PS4 Pro (launch model) and during certain moments the fan goes berserk. It turn on to the max speed and makes a high pitch noise.

Most of the times this happens during Cod Modern Warefare in the match making menu. Here it goes loudest. During gameplay it turns down a fraction. But still unreasonably loud.

Things I've tried

• Cleaned the internals
• Cleaned the heatsink with air
• Cleaned the fan
• Cleaned the processor
• Applied new arctic silver cooling paste to the processor.
• Applied new arctic thermal pads (the blue one)
• Ran a DB initialization

Things I've noticed

• When I took it apart it had barely any dust in it to start with. No build up in the fan and heat sink whatsoever.
• The original thermal paste was still moist/not dry

Thoughts

• I've read something about uncapped fps in menu's? Is there a way for a user to cap?
• Would disabling pro boost help?
• Would a clean install help?
• In retrospective, would sending it to Sony have been a better solution? :)
• Isn't this a software issue? Since the Fan changes speed rapidly. If a component is hot, wouldn't it take time to cool down? So the fan would keep in cooling it after the load stops, to gradually cool it down. And not end abruptly.
• I haven't tried this with other games. But I did recall it used to be better a few months ago.
• puts on silverfoil hat Is Sony bullying me to wards a PS5? :)
• Are there newer Pro versions that don't have this issue?

Do you guys have any insights or tips on this matter? I'm getting pretty desperate. I don't want to sell this unit just for it to become someone else it's problem. I would hope for a solution. I'm about to be kicked to the basements by my GF with the PS4. Since you hear it all across the house and it's WAY louder than a conversation.

--EDIT--

• Made a clean OS install. With install from USB. Re-downloaded just COD MW and still the same issue.