“because it absolutely seems like the booster was different in some way, or compounded on the first, or my Russian roulette theory stands to reason”

Russian roulette theory. The percentage of saline placebos went down over time. In the initial vaxx rollout, it might’ve been as many as most shots being saline. That way, they could reduce the optics of the adverse effects, of which there were still plenty. Then months later if there are still people dumb enough to spin the revolver, there’s less need to confuse them with saline, so might as well just give them the straight-up heart attack shot/ cancer shot/ immune system implosion shot.