I don't see any reason why Washington wouldn't be safe D.
I've caught a little bit of "Washington is moving right" national and local narrative at play because of the Seattle city election results last year but that was more of a rejection of extremist candidates than any sort of rightward drift. Similar to the Chesa Boudin recall... it doesn't mean we're all going to vote Republicans into the Senate now just because we decided not to legalize all crime.
Washington last elected a Republican to the US Senate in...*checks notes*...1994.
In an election cycle where the GOP won 7 of 9 House seats from the state.
Somehow I doubt that will happen today.