The graphics below list US Senators up for reelection in 2022. There are ten seats at risk of flipping, five Republicans and five Democrats (a few are retirements). Red border indicates either up for re-election or retiring.
Which Senate Seats are at Most Risk in 2022? (Ref: CNN)
https://www.cnn.com/2021/03/03/politics/2022-senate-race-rankings/index.html