Question Replaced laptop thermal paste, temps still go up when plugged in.

[FoxInFlames]

I have a pretty okay laptop (i5 9300H, GTX 1650, 8 GB RAM, probably 2400MHz) which used to get very high temps everytime (which, later i found out was, because the original thermal paste it came with sort of spread around the die instead of on it and was as hard as dried clay), so i replaced it's thermal paste with cooler master mastergel maker.

Now, on battery it's temperatures have become very better, it barely goes beyond 65 degrees on light gaming (old titles such as nfs most wanted 2005 on integrated graphics) but when i plug it into a power outlet, even when only teams and 2-3 tabs in chrome are open, it goes to 70-85 degrees, this isn't a very risky temperature but the fans work like crazy, and as soon as I unplug it, after 2-3 minutes the laptop goes back to 47 with near-silent fans.

Is there anything i can do? I also noticed that in the nitrosense app (my laptop is an acer Nitro 5, the 2019 model which has both fans together instead of apart, the 17.3 inch screen model) my cpu temp (assuming it's the package temp) runs around a lot, it would show 80 celsius, then suddenly jump down to 60, than goes 72, and so on (the 1650 always stays below 47 since it's always idle, i don't use it). Might be there is something wrong with my temperature sensors?

 

[FoxInFlames]

For a real example of the fluctuations in temperature issue, as soon as I start nitrosense it reads CPU temp as 84 degrees, and the very next reading drops down to 60 degrees, all while both fans are rotating at ~3000rpm, while GPU is at a constant 53 degrees