If you read through the the page I linked, it explains some of the people not running are running for other offices, such as governor of their states. Another factor is redistricting, which Republicans control in many states but not all. Those new districts will be in place until the next census in 2030.
If you read through the the page I linked, it explains some of the people not running are running for other offices, such as governor of their states. Another factor is redistricting, which Republicans control in many states but not all. Those new districts will be in place until the next census in 2030.