Might be a VRAM Issue if you only have 4GB of dedicated GPU memory.
FH5 is a very VRAM heavy game.
Use a program like RivaTuner to see all of your computers stats. You can get Rivatuner through MSI Afterburner.
Try to see if your temps get too high your vram gets used all the way or if your CPU reaches full utilization while playing. Also try plugging it into a wall while playing.
Edit: Didn’t look at the VRAM graph, it is most definitely your VRAM that’s your problem.