Compile Error: Cannot declare class Drupal__Core__Entity__Sql__SqlContentEntityStorageTrash665ed930f1d2d, because the name is already in use

Maybe it could help to get rid of PhpStorageFactory::get('trash')->deleteAll(); in TrashEntityTypeManager::clearCachedDefinitions()? Is there any reason these files need to be regenerated on every cache rebuild?

You would think that regenerating the class suffix when deleting existing classes would prevent this issue. Maybe this only happens when someone visits the site between PhpStorageFactory::get('trash')->deleteAll(); and \Drupal::state()->delete('trash.class_suffix');? I'll switch these two lines and see if the issue still happens.

FWIW, I added some `sleep()` calls in that code, executed drush cr and drush updb -y from the CLI, then browsed the site while the commands were still running, and I didn't bump into that error.

However, if you find that the MR makes a difference in your case, I've no problem with merging it :)

No it doesn't, the issue happened again since adding the patch.