The 990 had replaced the 980 on the AWD Model 3 starting sometime in 2019 apparently. And except for the fact that its power output is rated lower than the 980 (a subject of much debate), I haven't seen much info on it in general. Is it quieter, is the failure rate better, the same, or worse? So I've been paying attention to the complaints (noise / failures) to see if a pattern develops, but it's too soon to draw any conclusions.
Tesla's website has a parts catalog for all the models, and the Y has the 990 listed as well as the 980. So, I'm guessing that at some point, the 990 might show up in the Y (most likely the AWD).