What I looked up, your configuration is a laptop (i7-10750H is for laptops)
GTX 1650 ti starts to throttle (downclock) at 75 C° Safe limit is 86 C°. Regardless of brand of your laptop, I recommend checking this regarding your GPU. ->
Redditor finds a solution to the Dell XPS 15 7590's GPU throttling issue (notebookcheck.net)
There might be also be an issue with your CPU doing the same. You need third party software to check CPU temp and speed while gaming. I think MSI Afterburner might do the trick and also show information about your GPU regardless of GPU manufacturer and model. There is a youtube guide how to set it up to show information on overlay while gaming here:->
MSI Afterburner | How To Setup On-Screen Display (youtube.com)
While MSI Afterburner can be used to overclock, don't! I don't think that's your issue, but heat. Your CPU relies a lot on CPU's TurboBoost feature (up to 5 GHz what comes to gaming performance. If CPU is throttling because of heat (threshold is AFAIK 75-77 C°) that has impact to gaming performance.
Also one more thing, just to be sure. You keep your laptop plugged to wall when gaming and are not on battery?