Clock sync error is one of the most common reasons why credit card terminals fail to process a transaction.
GPS is one of the most common ways to set up a clock, and whilst the terminals and ATMs usually don’t get GPS time directly but through an NTP server the NTP servers do set their time via GPS.
Even if you have an atomic clock it’s usually set via GPS first.
GPS time is why you can actually get a coax to an external GPS antenna in most datacenters today.
After banks and stock exchange another victim of the clockpocalypse would be the Internet at large since whilst TLS itself doesn’t require time synchronization other dependencies such as certificate validation do.
Most modern computers are really really bad at keeping exact time without synchronization, it wouldn’t take much to knock them all out of sync and if GPS goes down it would be really really bad…
Oh and if that isn’t enough then modern cellular networks are also extremely dependent on GPS for both keeping time tolerances in check and for many other reasons.
If Russia knocks out GPS or there is a global GPS outage it will wreck the global economy in a manner that I don’t think most people can even comprehend.