[Kurona]

I think Saber's got a lot of holes in its storytelling like that, but thankfully they're for pretty minor details. I think you could easily explain away that they're dealing with Megiddo elsewhere or Solomon injured a lot of them or something; could have done with a few throwaway lines in the show but it's easy enough to imagine some explanations.

As for a real world explanation, I'd bet on their being given a heavily reduced role due to covid restrictions. It seems they were going to feature slightly more prominently from the scans we got mid-season.