Today if we detect concurrent modification of a snapshot repository then we mark it with `CORRUPTED_REPO_GEN` which blocks further writes to try and prevent additional damage to its contents. You can remove the marker by calling the register-repository API again, but this API will discard no-op re-registrations without taking any action. You can work around this by unregistering the repository first (which may be impossible if it's still in use for searchable snapshots) or by re-registering it with some trivial setting change (which seems hacky).

We should not consider it a no-op re-registration if the repository is currently marked with `CORRUPTED_REPO_GEN`, because doing this re-registration will re-read the repo contents and clear the corruption marker and therefore is not a no-op.
test/framework/src/main/java/org/elasticsearch/snapshots/AbstractSnapshotIntegTestCase.java
public static final String RANDOM_SNAPSHOT_NAME_PREFIX = "snap-";
    public static final String OLD_VERSION_SNAPSHOT_PREFIX = "old-version-snapshot-";
    protected static final int LARGE_POOL_SIZE = 5;
    
    
    protected static final Settings LARGE_SNAPSHOT_POOL_SETTINGS = Settings.builder()
        .put("thread_pool.snapshot.core", LARGE_POOL_SIZE)
        .put("thread_pool.snapshot.max", LARGE_POOL_SIZE)
        .build();
    @Override
    protected Settings nodeSettings(int nodeOrdinal, Settings otherSettings) {
        return Settings.builder()
            .put(super.nodeSettings(nodeOrdinal, otherSettings))