Was this not expected? PMs, like Philippe in 2017, tender their resignation following the legislative elections & get re-appointed if they won the elections, with a reshuffle undertaken as necessary. Had they won their majority, she would've tendered her resignation, Macron would've accepted it, & then immediately re-appointed her to head a new ministry, pursuant to the election result. Given the so far-unproduced lack of an alternative produced by the election, though, she stays for now. The question now is whether she (or somebody else under Macron) successfully pursues a permanent government, be that a minority functioning with opposition legislators on a case-by-case basis as necessary, or a coalition?
