The module is marked as still supporting Drupal 8. The kernel test implementation uses Drupal 9 and is not compatible with Drupal 8.
Test in question EntityBlockTest has the same protected visibility for $modules property as declared in Drupal 9 EntityKernelTestBase:
protected static $modules = [
While in Drupal 8 EntityKernelTestBase uses public visibility for $modules property:
public static $modules = [
As Drupal 8 is no longer supported, it's not worth releasing a major version change for this. Perhaps next release should drop Drupal 8 support from 1.x branch.
Remove Drupal 8 support from entity_block.info.yml
Closed: outdated
1.1
Code
Not all content is available!
It's likely this issue predates Contrib.social: some issue and comment data are missing.