I am using a texture pack wich makes your shields smaller, so they don't look that big when you are holding them in your off-hand. Everything works good before 1.16.210 update. After this update when i am holding shield in my off-hand its normal size. The shield have small texture in my inventory, but when i put him in my off-hand it look big, like without the texture pack. Its also bugged in 1.16.220.