[dv_dt]

So now I really wonder if it's some EMI from security equipment we run ourselves.

[ggm]

Believed this for a long time. ELINT has been a part of US embassies and the WH since forever. I think the overwhelmingly most likely reason is an own-goal side effect of counter measures.

[toomuchtodo]

Overly aggressive sweeper designed to energize passive only surveillance devices?

[dv_dt]

Smart (or dumb) equipment that dynamically mis/targets jamming signal to specific locations?

[ggm]

Beam forming comms, guess which people carry the new beam forming devices it's trying to optimise signal path to. (this was part of the OG 5G spec, to do agile tunable antenna stuff so you got diverse high bandwidth paths to specific devices in a "cell")