It wouldn't be prudent to post that they were specifically bugging a Supreme Court Justice.
But when you know what the Q team is and what it's doing and listen to what they DO say AND apply your thinking cap, then who else would be able to intercept a Supreme Court Justice's phone calls. This is spy stuff.
Q has written a LOT about listening in on cell phones whether they're on or off. And shared some of that intel.
They also wrote several times FISA works both ways. They wouldn't have to get a warrant on Roberts (though they may have), just some foreigner then make the jump to Roberts, just like the Obamites did with Trump's people.
FISA indeed does work both ways.
So Q is an un-named leaker