I'm going to take out the frogbit soon, but I've observed something I think is "interesting".
I don't think I have more than three "individual" plants, it looks like there are mother plants that are sending out runners that it remains attached to. Plants that look like they're dying are from smaller "mother plants", they're clearly out competed. When a "mother" plant sends out a runner, the runner immediately sends out 1 or two thick roots that are just going to substrate, the leaves are different too, they're "aerial" and are on stems above the waterline. I think there was a race to dominate, I think there is actually only two mother plants, and the rest come from them.
I could be wrong, but these plants aren't sending out those tiny single leaf frogbit, that we've all seen. Could these runners be to "go out and find better water" as opposed to what I'm seeing, which remain attached? ~4mm thick connection roots.