Fatigue is applied when opening a shulker box

[vsvleo]

Tell me, please, what could be the problem?

[Carl_71]

There is no problem, this has been done by staff. If you read chat there is a message that comes up every so often saying that this will happen. It also tells you to run 3 blocks after closing the shulker to remove the mining fatigue.
Listen to fellow players, they have also stated this in game.

[vsvleo]

thank you very much. everything worked out!