Ukraine

if you expect drones to be used, it makes sense to jam 2.4ghz, 5ghz (communication with drone) and 1.6 ghz (gps signal), maybe some more obscure bands like 900mhz and 3.2ghz (communication with drone) but if you make custom drone that uses, say, 7ghz frequency for communication, that's outside of normal bands and it's most likely not jammed because there's no point if it was never used. just filter everything else out and you're good to go. jamming only thin bands instead of blanketing everything makes jamming effective over much larger area with the same power. you can even make drone use some band that's used by, for example, enemy's radar that's currently not in area, so that band is not jammed by EW device but also not jammed by radar

But the drone can enter autonomous mode when it happens and direct itself with lidar, gyroscopes and cameras I imagine.

and how it's guided? as in, how it's communicated with operator? because it's happening here. laser in free space would probably require another drone with line of sight to the first one, as a repeater, and this one also needs to be not jammed, otherwise you need line of sight from drone to operator and this would be pretty hard over distances drones are used now

anti-radiation drone (like anti-radiation missile) would be pretty nice idea but this one is clearly guided manually, like every other FPV drone. it would also be much bigger (needs some 15x15cm panel with antennas as seeker at minimum and some circuitry for extracting direction from signal)

I’m pretty sure “heavily jammed” means most radio frequencies will be jammed.

Why arent Russians jamming everything? Are they stupid?

if you attempt to do this, you get three pretty big problems.

1. you want to jam only the enemy's frequencies. if you jam everything, you are denying yourself communications, both civilian like gsm or wifi and whatever specialized devices you might have, and more importantly you are jamming your own radars. things get trickier when you and your enemy are using the same bands, like 2.4/5ghz wifi for drone control. sometimes you don't see EW used for this exact reason

2. power spectral density drops massively, decreasing effective range of your jammer. there's no hard border between jammed/not jammed, there's a gradual transition instead. when you put lots of radiation in bands that nobody uses, you're limiting jammer for no reason. it's better to blare noise only on narrow bands where there's actual traffic. can you jam everything from 2 to 3.5ghz? sure, but if you really need to jam only 2.4ghz wifi band, then you're limiting range by about 4x or so, everything else being equal. additionally, things get broadband and it's bad, because all components need to be broadband, which is harder, heavier, more expensive, or you need to bundle what is effectively several jammers next to each other, some of which would only jam, say, friendly radar

3. if you're jamming, you're jamming for everyone. this also means that you can't use electronic surveillance on bands that you're jamming, for example you can't locate wifi transmitters or drones if you jam wifi bands

no, "heavily jammed" does not mean "all bands are jammed" as evidenced by fpv drone being controlled by operator and receiving video output, which means that whatever bands they used were open. "heavily jammed" more likely means that common bands like 2.4ghz or gps bands had large spectral power density of whatever they used for jamming (does not have to be white noise and probably wasn't)