No but them both using the same physical principle seems reasonable, especially given that the US used this as well. The purpose is to store passive electronics (say, for eavesdropping) with a frequency specific RLC circuit providing power in the walls, when they're built. These cannot be found by spy detector gadgets because except at one frequency there's almost nothing to be found (there is a "passive cavity", which will not easily be identified as a spying device but can be used to eavesdrop, and more modern versions are the size of an rfid tag, 1/4th the size of a grain of rice is quite doable). They need remote power, however. So you need to direct something at them strong enough to power the circuit, which then sends the data back, and you need to do this from a few hundred meters. There's technical reasons (easy availability of generators) why you want(ed) to do this with microwaves.

https://www.eetimes.com/eavesdropping-using-microwaves-adden...

A misconfigured device used by the diplomats might be a bit more likely.

Maybe the Chinese diplos in Cuba did