Duplicated pubkey error while creating a new minipool with credit

[europaer]

I am migrating 16 to 8 ETH minipools and after issuing the refunds and having enough credit balance I get this error while trying to create a new minipool:
Could not get can node deposit status: Error getting transaction gas info: could not estimate gas limit: Could not estimate gas needed: Reverted Validator pubkey is in use

What might be causing this? My clients are correctly synced, with many peers and everything's working just fine.

Thank you