I don't think a standard has been defined yet or will be any time soon. Virtually every series I watch these days has a season that's 10-13 episodes. But sometimes less. And it'll just go for however long makes sense. I unintentionally and accidentally binged an entire season of a show called Dirty John with some friends yesterday. At first we thought it was a movie, then it turned out to be an eight-episode season. But then we got hooked and kept on watching to the end. Which was probably the effect the creators were going for.
I noticed that with Stranger Things, they're unofficially calling each season by the title and whatever number the season it is, like soon it'll be Stranger Things 4. So, ultimately, I think they'll keep making streaming seasons shorter and shorter until it finally crosses over from "short season" to "long movie", which might get a "sequel" season.
I'm basically treating Picard as a second chance to put him into a series of "movies" that actually does the character justice this time.
For those of use who've watched British TV for decades, short seasons are quite familiar. Mind you, I watch shows these days that range from full 16 hours or so seasons to seasons as short as 3-4 hours. I don't really think that long form 20+ episode series will go the way of the dodo until streaming is the only choice. However, now that every US broadcast network actually has a streaming service, that turnover could be happening sooner rather than later.