If you are holding 2 shields at once, block with the main hand shield, and switch to another main hand slot, it will automatically start blocking with your off-hand shield. However, if you do the same thing but instead throw the shield on the ground, it will not automatically start blocking with the main hand shield.
Steps to reproduce:
Hold a shield in both hands
Block. Notice you block with your main hand
Switch to another inventory slot. You will begin blocking with your off-hand.
Stop blocking and switch back to the original shield.
Start blocking again.
Throw the shield on the ground. You will not be blocking with your off-hand.
Linked issues
Comments

That's not the issue at all.
Yes, it actually is the same as MC-231097. You just haven't thought about it enough.
it still slows down the player because the client still thinks that you are using the item even though you have already dropped it. This also prevents other items from being used due to the way that right click actions which slow you down are coded.
Thank you for your report!
We're tracking this issue in MC-231097, so this ticket is being resolved and linked as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
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