My laptop's APU is power throttling but fine when I unplug and unplug the AC

[Ovila3k]

First of all, i'm not trying to get 144 fps from a notebook. My current laptop is an HP envy x360 13 powered by a Ryzen 5 2500U APU. This is not meant for gaming I know, but most of the time it copes games like Fortnite (hate all you want) just fine. I just started having an issue where the Fps drops considerably for what I think is power throttling. The CPU is mostly at 40-50% so the GPU should have all the power it wants, and yet in downclocks from around 800-900mhz down to 250-300. The temps are about 70 degrees Celsius which is warm but not super hot, and strangely enough, if I unplug the AC and replug it in, it works fine for just under 2 mins, and then the cycle repeats. All the drivers are up to date and I have the back of the laptop propped up making sure the intake fans are not blocked.

Any help would be massively appreciated, really

 

TLDR;

My laptop has its GPU downclocked heavily but is fixed temporarily when AC is unplugged and re plugged. 

[TheBean]

what is the wattage of your charger? (usually written as watts or you can just multiply output amps and output voltage)

[Ovila3k]

It's a 45 watt power supply, but I feel like that should be enough considering that the whole APU uses 15 and that the CPU isnt even on a full workload