Fan really kicks out and temp goes below normal so much

ThinkPad E14 Gen 2 AMD 4700u Kernel 5.12.2-1
I was normally getting 40-50’C for temp and fan was usually doesn’t needed to work. But for the last couple weeks it goes to 70’C out of nowhere and fan works on full rpm. Its really annoying I am just studying on a pdf etc. on okular and that is the only thing that is open.
I am using the laptop 8-10 hours a day for 8-9 months. There is no dust on my desk I keep it very clean for laptop. So do you guys think I should replace the thermal paste and clean inside(which i think its clean enough to not go up 70degree) or is it software related maybe?

For the sake of testing, open your PDF in another software?
Check CPU usage?

But I would say if CPU is heating, then fan will ramp up, it is expected behavior. You can keep your desk clean, the air is filled with dust particles that will eventually stack in cooler, so if computer is not new it is possible there is dust in it.

//EDIT: but your computer seem relatively new.

//EDIT2: try kernel 5.10?

I just gave an example for pdf. It happens all the time. Normal browsing, online class etc.
I check cpu usage when it heats up but it looks same.

I though about changing kernel and I’ll try it now thanks.