kernel_task taking up 800% of CPU on MacBook Pro 16

When my MacBook is connected in closed-clamshell to my dual 2K monitors or my 4K tv, kernel_task quickly takes up to about 800% of CPU and slows everything down. The Mac is practically unusable when this happens.

I've already reset my SMC and NVRAM, and that didn't fix it. I also had the fans completely cleaned - they were covered in dust (there is no way to avoid dust where I live - unless I air condition my room and keep it closed at all times. ACing is going to cost a lot so that is not an option for me at the moment.) I thought getting the fans cleaned would help, but it didn't.

What else can I do? Should I take this in for repair? Sort of freaking at the moment.

My Mac:

• 2019 MacBook Pro 16
• 16GB RAM
• Radeon Pro 5300M 4GB
• macOS Big Sur 11.2.1

Here are two screenshots of the recorded temperatures at various sensors and my Activity Monitor.

Any help would be appreciated. Thank you.