hi Robin--
State-to-state was published, last year. It's just difficult to find with the search functionality on census gov website.
Try here, direct link: https://www2.census.gov/programs-surveys/demo/tables/geographic-mobility/2021/
PS: oh, maybe this explains:
"Notice for ACS 5-year Migration Flows Break in Series
Beginning with the American Community Survey (ACS) 5-year 2017-2021 estimates, The U.S. Census Bureau’s annual ACS 5-year migration flow data product will transition to a new flow format, linking recent movers’ previous residence state to their current residence county. This notice summarizes the series break in the 5-year ACS migration flows table package."
--todd graham