No, it has jurisdiction over crimes on Ukrainian territory, regardless of the actors. (Were Ukraine a state party, and not a state that had acceded to territorial jurisdiction without being a party, it would also have jurisdiction over Ukrainian personnel, irrespective of territorial considerations.)
> So Britain ( party to ICC ) could murder children in Libya but that’s okay
No, because Britian is an ICC party, ICC has jurisdiction over its troops anywhere without needing territorial jurisdiction, which is why there was an extensive ICC investigation and report based on allegations of UK war crimes in Iraq. Were reports made to the ICC of UK alleged war crimes in Libya, they would be subject to its jurisdiction.