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.
server/src/main/java/org/elasticsearch/repositories/RepositoriesService.java
indices = new ArrayList<>();
                }
                if (indices.size() < 5) {
                    indices.add(indexMetadata.getIndex());
                }
                count += 1L;
            }
        }
        if (indices != null && indices.isEmpty() == false) {
            throw newRepositoryConflictException(
                repositoryMetadata.name(),
                "found "
                    + count
                    + " searchable snapshots indices that use the repository: "
                    + Strings.collectionToCommaDelimitedString(indices)
                    + (count > indices.size() ? ",..." : "")
            );
        }
    }
    private static boolean indexSettingsMatchRepositoryMetadata(IndexMetadata indexMetadata, RepositoryMetadata repositoryMetadata) {
        if (indexMetadata.isSearchableSnapshot()) {
            final Settings indexSettings = indexMetadata.getSettings();
            final String indexRepositoryUuid = indexSettings.get(SEARCHABLE_SNAPSHOTS_REPOSITORY_UUID_SETTING_KEY);
            if (Strings.hasLength(indexRepositoryUuid)) {
                return Objects.equals(repositoryMetadata.uuid(), indexRepositoryUuid);
            } else {
                return Objects.equals(repositoryMetadata.name(), indexSettings.get(SEARCHABLE_SNAPSHOTS_REPOSITORY_NAME_SETTING_KEY));
            }
        }
        return false;