We realized that used memory of our application is increased dramatically in case of using with NVIDIA GPU. 
And then we tested template OpenGL examples to find out whether memory increase problem is depend on our application. We run template OpenGL examples which are dice rolling and triangle turning and same memory increase problem is also observed with defined QT versions above in case of running with NVIDIA GPU.

Our application has at least 2 releases in a year and it is being used on customer sides. We're using same Qt version for almost 2 years. Even though we did not upgrade Qt version, we observed this memory increase problem with new NVIDIA drivers released on 2025.(This is our assumption)  Qt version on our product is planned to upgrade to 6..9 at the end of this year, But It seems that same memory problem is also available on Qt 6.9.1.

Various QT versions and NVIDIA drivers were tested in different computers. Memory increase problem is common observation on all tests 

test environments

Qt 5.15.14, NVIDIA Graphics Driver 566.24 (32.0.15.66.24)

Qt 6.9.1, NVIDIA Graphics Driver 566.24 (32.0.15.66.24)

Qt 5.15.11 NVIDIA Graphics Driver 566.24 (32.0.15.66.24)

Qt 5.15.10 NVIDIA Graphics Driver 566.24 (32.0.15.66.24)

Qt 5.15.10 NVIDIA Graphics Driver 573.42 (32.0.15.73.42)

Qt 5.15.15, NVIDIA Graphics Driver 566.24 (32.0.15.66.24)

Qt 5.15.14, NVIDIA Graphics Driver 572.16 (32.0.15.7216)