Both military and civil GPS signals are L-band. Any jamming that runs across the L-band will hit both of them. And since the frequencies are publicly available (and it is possible to confirm that they are correct with your own detecting equipment) it is not any harder to jam the purely military frequency versus the civil and military frequency. The only thing is having more frequencies to jam should mean less power on any given frequency for a given amount of power, especially since you would probably want to jam BeiDou and Galileo signals as well (all also on the L-band). I mean, since Ukraine and Russia can buy things on the open market, they could buy BeiDou receivers just like GPS, so I would expect them to target all of those frequencies.

Block III GPS satellites added a new feature, designed to help the military signals defeat jamming. They added a "spot beam" - a high gain directional antenna capable of covering an area about 200km wide with 20db extra power, to try and burn through jamming. This spot beam is only used for military signals, and it requires extra processing on the receiver to use (since the satellite still has the earth-wide antenna broadcasting the military signals, a military receiver inside the spot-beam area would see two different signals from the same satellite, absent jamming).

During the Biden administration, at least, USAF ISR assets spent a lot of time running race-tracks just at the edge of Ukrainian airspace, monitoring events in the country, and I would expect that would be something that would be a good use case for the spot beams, though I don't know about Ukraine ever getting any of those receivers, and I would not expect coordination with the USSF on pointing the high gain antenna to support UAF operations even under Biden, but all of that is my speculation, I haven't seen anything on where these high gains are pointing.

They shut down the western steel work radar because of power cost increases after Chernobyl blew, combined with the improved value provided by surveillance satellites.