You aren't alone, I've been having this issue since V40 as well and it's completely ruined VR for me. Without sharpening, everything is a massive blurry mess that even Reshade sharpening or injecting FSR/CAS sharpening won't fix. Oculus' own solution...

Can also confirm ever since one of the V41-V43 updates that Link Sharpening is completely broken on Quest 1. No frames are dropped, no reprojection, no strange issues with CPU/GPU usage, 2.2Gbps USB3 Cable, but massive stuttering and jittering in Ocu...