Iris xe underperforming while gaming

Recently I started having issues with Intel Iris Xe performance. To be exact, I experience often stuttering while playing Valorant and CS2, and FPS tends to drop from around 70 to below 20-15 several times a game, averaging around 50fps with less than 10fps 1%low. It also makes no difference whether I run the game on Very low, Medium or even High settings, the FPS changes insignificantly, yet the problems remain. Also worth noting that I was able to play valorant at around 80FPS on high settings a few months ago, with no noticeable drops. The system in question is an Dell vostro 3520, with the following specs:  i5-1235u, 16GB RAM (16x1)  256B SSD, Intel Iris Xe.  In addition, I couldn't identify any bottlenecks myself. CPU and RAM usage are usually below 60% when I play, and GPU usage hovers around 35-60% which is really strange (also, the gpu clock doesn't even exceed 600mhz). I ran the Intel Processor Diagnostic tool, and the Dell Diagnostic via Support Assist and there was no difference. I also performed a clean Windows 11 Pro installation a few days ago, updated the drivers (both from Intel's website and Dell's website) but the issue remained. I even tried to roll back old drivers, but it only has gotten worse. Also, the power mode is set to Best performance.  Please help