1 cpu core running the game and basically gpu usage

I believe all versions are affected by this but it seems that Minecraft is only 1 physical CPU core and doesn't use the GPU at all, which causes even a ryzen 7 3700x mixed with an RX 6800XT to get 30fps on a benchmark map now that still is playable but for lower spec PC's they will need all cores and the GPU to be used since Minecraft is always adding on more, as you can see by the video settings I'm using the fps could get lower if I raise the biome blend and the render distance, which I did and was getting 18-25 fps (with it averaging out on the low 20's). I know a fix for this would be to re-code the whole game but Mojang is worth 1.6billion USD I find it hard to believe that you can't afford to have a small dev team re-code the game for java players (yes it could take a long time but the original players who stick on java will gain a massive boost in performance low end and high end) (I also didn't provide another screenshot of task manager showing CPU usage cause there were no changes)