We can cause a prepare conflict if we set a wildcard index as multikey as part of a prepared transaction and then try to set it as multikey through a write separate from the transaction.

The conflict comes from when we insert keys into the index itself for wildcard indexes (multiMetadataKeys is populated by the wildcard_key_generator). I think that is done in the same wuow as the transaction, which means that it will generate a prepare conflict if we try to write on top of it.

I suspect this would be resolved if we did these writes in a side transaction block, like when we set the index as multikey.