Air carrier pilot reported after GPS jamming occurred enroute they did not recover full navigational capabilities.

Narrative

GPS Spoofing and anomaly occurs within 30 minutes of takeoff as we approach ZZZZ and the ZZZZ/ZZZZ1 border. This reality leaves our GPS open to bad data strip and expired data for the acquired satellites. This same satellites can be reacquired over Location X many hours later during our oceanic crossing; and particularly if in half-tracks..The pilots operating post spoofing in the ZZZZ1 region may have acquired other satellites elsewhere and observed normalized GPS position and FMC navigation but; when the previously acquired satellites are reacquired over the horizon during the oceanic crossing then the bad data strips related to the reacquired satellites; if the expired timestamp has not occurred; the aircraft will now have spoofed to position to the oceanic crossing and the aircraft will be unable to comply with RNP 4.0 or worse RNP 10.0. This happened to our flight a few months ago as we experienced an RNP upwards of 12.9. We were able to reach OACC (Oceanic Area Control Center) and continue at altitude and thus safely complete the flight without diversion for a fuel stop. Other flight may have to descend out of oceanic crossing. We were on a random route and well north of the tracks and then only crossing the northern most tracks neither of which were half tracks. The context of this topic is the recency of experience and fleet crewmember experience.Some mitigations: Do not plan ZZZZ flights in the midst of the tracks but rather only on ones which can accept RNP 10.0Use random routes on the northern most two side of the tracks to allow OACC to accommodate our very likely GPS anomalies.And; proactively consider developing a procedure for flights traversing known areas of spoofing whereby we deselect GPS updating in the FMC prior to the spoofing. This prevents certain data from becoming imbedded" in the system so that once out of the region the GPS operates normally.Develop the briefing to address these contingencies; and develop a proper GPS anomaly checklist that actually addresses and advises crew to better prepare for airspace restrictions.To do otherwise is to normalize non-compliant operations and to normalize less than safe operations which we do not tolerate elsewhere.We must never normalize unsafe ops; currently; the regularity of spoofing and operating without Terrain; EGPWS; and weather features impacted; and auto tuning; and thereby without opportunity to fly RNAV approaches in terrain but; which are frequently required by depressurization routes is the normalization of unsafe ops given that better data is available and mitigations are available.In the context of the TEM (Threat and Error Management) at this airline; if a potential spoof to position will occur or has occurred we should and ought to consider the value of SSR (Secondary Surveillance Radar) routing in RVSM airspace versus G airspace if these resources exist.We must strive to be the industry leader and not accept complacency!"