So basically a few days ago I noticed a visual bug that made any blocks that were away from me have a blue outline, as if I were hovering over the block with my cursor, except the outline was blue, kind of like the sky. I thought it was an issue with Optifine, so I opened the game with vanilla 1.16.4, but the bug was still there, and same with 1.16.5. I've searched everywhere and there is basically no recorded sightings of this bug, so I hope this gets fixed soon.