AMD Ryzen 9 3900 is processor manufactured by AMD and launched in Q4 2019 . It's using AM4 socket. It has 12 cores and 24 threads with clock of 3.1 GHz that can turbo clock itself to 4.3 GHz . This processor is used in Desktop devices and can consume up to 65 watts of power .
AMD Radeon RX 6600 XT is graphic card manufactured by AMD and launched in Q3 2021 . It's using PCIe 4.0 x8 bus type. It has core clock of 1968 MHz and 8192 MB (8GB) of memory . It supports OpenGL 4.6 . This graphic card is used in Desktop devices and can consume up to 160 watts of power .
This configuration has 19.0% of graphic card bottleneck .
When playing games your processor won't perform on maximum possible performances (won't be utilized to the maximum), because you graphic card cannot handle delivered data fast enough. This theoretically means that utilization of you graphic card will be on maximum and the potencial of processor will not be completely used.
Graphic card bottleneck is better, than processor bottleneck, because utilization of your graphic card will be on maximum and you will experience maximal performances that your graphic card offers. Also your processor can handle some other programs in background because it won't be maximally utilized.
You can resolve this by upgrading your graphic card or by downgrading your processor. Downgrading your processor doesn't make much sense and in that case is better to leave current processor in you computer, because you can run more background task that won't interupt your gaming experience.