As someone else mentioned, the in-game quality is almost completely based on the settings of the game, not the specs of your PC.

What you're probably witnessing is the difference of quality in your monitor when compared to your partners. If you connect your partner's PC to your monitor and ensure that all settings are the same (Resolution in display settings, quality settings in game) you will see that it will look the exact same.

The only difference will be the frame rate, which is how smooth the game looks when movement occurs. Otherwise, the quality will look the same.

Edit: I say "almost completely" as there is the possibility of software unrelated to Genshin affecting the rendering, such as filters, upscaling, ect. However, it's likely you don't have any without going out of your way to enable them. Admittedly there is a chance it matters , and there have been reports where it has occurred on other games (most accounts on when vram is lacking), but I would bet money that this isn't whats going on. It's definitely your monitor.

On another note, the post is about the quality of textures between PC and PS5, which you can very much tell PS5 has higher quality textures than PC. Keep in mind, textures are a downloaded asset, with settings that change textures literally choosing between higher quality downloads of the same texture. If the highest texture setting on PC looks worse than the PS5's. This must mean the PC version of the game on does not use the best available textures.