Kernel_task process takes 700% of my cpu when I plug in my external monitor

Hello,

this afternoon I started getting this really annoying issue on my MBP 16" (2019). For the past year, I've always used my laptop with an external monitor using an USB-C to Display Port cable. Never got a single issue. Today I plugged in my display port cable like any other day and after a few minutes, my MBP became pretty much unusable due to kernel_task using over 700% of my cpu. I plugged out the cable and it came back to normal in a matter of seconds.

My MBP is fairly new (less than one year old) and on top of that, I got it cleaned from all the internal dust less than 3 weeks ago. I never had overheating issues. In fact, even though kernel_task completely takes over my CPU, the temperature doesn't even get that high (roughly 60-65 degrees Celsius).

I've tried the following but nothing helped so far:

• Updating to the latest BigSur version (11.3 as of today)
• resetting SMC and PRAM
• Cleaned my SSD from about 50 GB of useless files and apps
• Set the fan to run to the maximum in order to get the temperature even lower (even under 60 degrees Celsius, the issue persists)

Any help would be greatly appreciated. I'll keep this thread updated in case I manage to fix it myself.