A significant portion of 5G bands are in or around 2.4GHz band and 5GHz band.
Jammers aren’t usually meant to be perfectly selective, just putting out tons of power from say 2.1GHz to 2.6GHz would ruin tons of 5G bands as well as pretty much all wifi running on standards older than 802.11ac.
If you study signal processing you’d learn that it is in many cases just mathematically impossible to generate an arbitrarily narrowly focused signal on a given frequency. It always spills over into frequencies above and below to some extent. There’s been decades of work into developong filters to try and get those edges crisper and tighter, and the jamming equipment doesn’t use any of that shit, it’s job is to turn on the firehose and blast.
