She still can apply for pre-settled, and there would be no reason she couldn't get it if she has a national insurance number. I've been in the country only for 3 or 4 months and got pre-settled status within a day of applying.
There is currently no system in place to allow re-entry for people with either "settled" or "pre-settled" status (that's why this announcement is mad.) But your girlfriend should 100% absolutely as soon as possible make sure she has pre-settled status.