Performance issues

Hi, i have recently purchased a AN517-51 nitro 5 and after playing GTA 5 or any game in fact on AC adapter (From 100% + High performance plan on both GPU and CPU) the games start to lag heavily after battery drains to 95% while on AC and starts charging and the lagging starts to make gaming impossible  .

Seems soon as it starts to charge the battery on AC ( after draining from 100-95% )both CPU and GPU clock down severely for a min or so and make the games unplayable the entire time even if recharged back to 100% while playing with heavy lag.

I have read multiple threads here but no solutions to this problem. I thought this is a gaming laptop? but only games for 5 min then turns into a potato....... Both CPU and GPU Temps and all are under 75c so its not thermal throttling and seems to power throttle soon as battery starts to charge from 95%-100% and even once back to 100% it still power throttles while gaming .. Looking for someone to please help with this problem. There is also no battery reset button on my model and having to use 3rd party applications to Modify cpu to run slower and undervolted is not acceptable !

With kind regards