Question Laptop slowing down on charge

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From last 3 4 days laptop is stuttering and slowing down when I connect the charger. CPU speed goes down to 0.79GHz and sticks to it as well. But on battery no such issue. Also tried to disable BD_PROCHOT from throttlestop through which normally it works fine on charge but in games it gives 10fps. Tried power plan change and everything. Also updated to windows 11 as well to fix it but no luck. PS - thermals are very good not going above 60 changed paste some months back. Battery was bit swollen when I opened to change paste some months ago could that be the reason? Please help if possible.
Laptop - HP Pavilion Gaming dk0047tx i5 9300H and GTX 1650 4GB I have 16GB RAM and 1TB HDD + 256 SSD (around 4 years old)