Dedicated GPU memory

Hello. I noticed such a feature that in games in the task manager, the allocated GPU memory is maximum, that is, approximately 7.9 out of 8.0 GB, and the total GPU memory is 0.1 out of 8 GB. Tell me what the matter can be or should it be? Rx 590 video card, ryzen 2600x percent. Vertical sync enabled. FPS at maximum speed, even in a rather old game like far cry 3, sometimes sinks to 45-50 even with msaa turned off, you just have to set high settings so that 60 fps is stable. In GTA 5, just at high settings with completely disabled msaa in the city, in some places it also sags to 45-50 fps.