If I pick up eny block from the floor so out of nowhere starting glitching some white plate in my other hand and this is happend also sometimes too when I was just staying and doing nothink in my area.
This one happend only me when i just upgrade to latest Optifine versin on 1.21.7. Before I was playing on 1.21.4 and everythink was perfekt up to today.
Mods, including Optifine, are not supported. Please try replicating the issue in vanilla Minecraft.