In the antithesis build when we turned on the add_remove_random_shards flag on the add_remove_shards.py we had issues; most probably that the genereated fuzztest was adding the shard before the hook does and then we had a clashing name.
The saga is BF-37842
We tried to avoid fuzztest to generate add and remove shard commands during test generation in SERVER-105954
After that the BF showed up again.
Since we don't have the generated fuzztest nor the exact parameters of the generation, the person who gets the ticket should get those information and double check if the original hypothesis (most probably that the genereated fuzztest was adding the shard before the hook) was correct and how to fix it.