GPS spoofing is also a thing. Here's a paper where they are able to spoof time while letting the receiver think it hasn't moved (much, within error bars): https://ieeexplore.ieee.org/document/6451170
That paper is in context of power grid equipment, but the GPS attack generalizes.
https://www.ofcom.org.uk/spectrum/information/gps-jamming-ex...
https://www.navcen.uscg.gov/?pageName=gpsServiceInterruption...