Strategic skip block withholding can enable double spends for validators before a macro block

[hrxi]

A validator can bring itself into a position where it has the last necessary vote for a skip block. Since chains with more skip blocks have higher priority, this can be used to roll back a transaction. It is mitigated a bit by the fact that validators will re-add transactions that were rolled back to their mempools, but this cannot be guaranteed by the protocol.