Thats one way to play with numbers. The other is it was R, flipped D and was expected to flip R again especially with the president numbers in the tank. That didn't happen.
I lived in that district until a year ago. It has been becoming bluer for years, and that was accelerated over COVID with young liberals moving in to get away from the city.
Faso only won in 2016 because;
1 -He ran against an extreme liberal (Zephyr Teachout) who didn't live in the district until she decided to run.
2 - Trump's coattails.
Before that there was a Republican Congressman who was extremely popular in the area, and who (in his last election at least) ran against a guy whose also moved to the district in order to run for Congress.