Ionization chamber smoke detectors have a tiny grain of Americium in them, which is radioactive. However, the radiation is almost entirely alpha particles which are relatively low risk as they don’t penetrate skin particularly well.
They are also still sold, though you should buy the other kind (which use light beams instead) because they’re significantly better at their jobs.
It was 100% because the existing Electron version they were using was ancient, a giant pain in the ass to update, and represents exactly zero revenue for them so they hadn’t bothered putting anyone on fixing it. Every tech company has the ticking time bomb in the corner like that.