Since 1.20 was released, the Breathing Bobbing on some items such as the apple is incorrect and swinging with the affected items is also incorrect.
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Can confirm. The video linked in the Reddit post below was recorded in 1.20, but the issue persists in 1.21, and as you can see, bobbing for the string is more intense than the bobbing for the sword or the redstone lamp. Same the same thing is present with wolf armor.
Video from Reddit Comparing Idle Bobbing Between Bedrock And Java.

dupe of MCPE-172710