After vast research we found out that the only stakepools with validators hard lagging (>800ms) are @MarinadeFinance and @xShinPerfPool. Reported to both pools about the findings, this cluster was funded by the same validator BT8L...gziD. They are all anonymous validators without any reputation, with some also sandwiching. Maybe is time for pools to be more criterious about where they delegate their stake so Solana is not put at risk.