I am currently planning to upgrade Opensearch version from v2.2.1 to v2.6.0.
As there is no information on the backwards version compatibility for v2.6.0 in the Opensearch documentation, Please let us know if OS v2.6.0 supports Rollback to v2.2.1 with no loss of data ??
Rollback to previous Opensearch version is not possible without data backup.
Take snapshots (backups) before doing the upgrade.
You could try, Basically would include a repo configured, install earlier version and upload the backup repo set. Not sure what will happen thou.