This surely isn't a surprise to anyone paying attention, e.g. (taken from a bigsoccer forum post) The US made the U20 WC semifinals or final in 5 of the first 6 editions, winning 3. In the ensuing four tournaments (since '14) they've finished 4th once, and failed to make the semi's let alone the final in the other 3.
So, the writing has been on the wall for years that a shift is coming. The explosion of the women's game in Europe (specifically) with the pro teams carrying women's teams also has seen Europe following their "normal" path for developing talent straight into their academies (pick the best, not who can pay the most) and going full time earlier (teen years), not wasting 4 years of development in college.
USWNT can still hang and "on any given day" beat anyone, but there are multiple teams that, "on any given day", can beat them. The aura is gone, and aura is an enormous psychological advantage at this level.