Not that trivial with the huge amount of frequency hopping it does, or is it?

It does not hop much. Spectrum is heavily regulated. To get certified to sell you must comply with a lot of regulations. What usually the smart jammers do is to disrupt the handshakes. Or you can bruteforce with couple of kilowatts white noise. You can also install the app and cause packet drop. Or all three.

I expect on the next protest people suddenly to find out those kind of networks to work poorly.

It does not hop outside of the defined unlicensed[1] 2.40-2.48 GHz band. If you can block that whole band, BT doesn't work.

[1]: In the US; it's complicated. Tl;dr is http://afar.net/tutorials/fcc-rules/ , much much more verbose is https://www.ecfr.gov/cgi-bin/retrieveECFR?mc=true&r=PART&n=p...

2.4GHz band is the GSM band here in HK so would be major disruption of general communications which is why they cant do it. Yes GSM runs on other bands like 1900 but majority of phones in Asia use GSM as backbone, and LTE over this freq, so unadvisable to block that freq. What could be done is to flood the mesh from myriad devices running the same app or derivative.

I can't find 2.4GHz as a GSM band: https://www.spectrummonitoring.com/frequencies/frequencies3...., https://m.gsmarena.com/network-bands.php3?sCountry=HONG+KONG, https://www.frequencycheck.com/countries/hong-kong

jam the entire 2.400-2.485 GHz spectrum?

What's the practical range of any jamming attempt? Wouldn't the government have to put jammers in every corner?