Using Shield while going into nether through the portal makes the shield auto-usable, even when you are not using the shield still it will block attacks and at the same tiem you can even attack, break bloc, mine or do anything

Take a shield in off-hand, press right click and shield-up then keep the shield up and step into nether portal, when you go through it, any attacks on you get blocked even if you aren't using the shield and also at the same time the attacks are getting blocked you can attack mobs, players or do mining, etc. This bug is shown in many YouTube videos as well.\

Video is having large size here is the link
https://screenapp.io/app/#/shared/9569c54b-d1c1-4742-adf0-76aebb6c5715