HP Pavilion Gaming Laptop slows down when charging

Product: HP Pavilion Gaming - 15-ec1025ax
Operating System: Microsoft Windows 11

Hi, I've been using this HP Pavilion gaming laptop for around 2 years and for a while now, I've noticed that the laptop slows down measurably when plugged in.

I use this laptop for gaming and running various CAD software and didn't have this issue until a few months back. At first I thought it was some kind of driver issue, so I cleaned up a lot of files, updated the OS and drivers and also ran a few anti-virus scans for good measure but to no avail. Just to be clear, the laptop works absolutely fine when it runs on battery power (I've confirmed this multiple times).

Looking around the internet, I realised that the AC Adapter might be a problem and sure enough, the connecting pin of my charger was bent. Also there's slight damage around the charging port. My charging device is a 150W AC Adapter. However, even after buying a new one, there is no change in the performance when plugged in. I tried running some diagnostic tests on the new adapter and it says the the HP Smart Adapter has failed to respond.

After this I gave the laptop to a repair shop and they said that a circuit containing the charging port had been damaged by an ant infestation. Anyway, they said that they fixed it and it worked normally for a while after that but then the issue started again. I'd just like to confirm if this is indeed likely to be a hardware issue and if I got scammed by the repair guys. I'm planning on moving to a new country soon and I'd like to get this issue resolved before that, since I'm not really a position to buy a new laptop right now. The AC adapter also still fails its diagnostic tests and I keep a getting the "Smart Adapter feature has failed to return valid data" prompt.

I hope someone can help me out.