Do you happen to have a scheduled monthly full backup? If so, it makes sense that you have more restore points than configured. The agent can only purge the oldest VBK (full backup) and VIB (incremental backup) once the most recent backup chain (VBK and VIBs) have reached 30 restore points.
Can I manually delete the files in the NAS folder or how can I identify the issue?
Manual deletion is not recommended, as it may lead to broken backup chains. If you have a single backup chain (1x VBK and multiple VIBs) and you delete the oldest VIB files, you won't be able to restore from the subsequent restore points. Every previous VIB file in the chain is required if you want to restore from a specific day.
No, there is no specific "tool" for this. If you don't schedule regular full backups, you end up with a forever incremental backup chain. Each day, the full backup should be merged with the oldest incremental restore point.
I can only imagine there might not be enough space on your storage to run that merge. But your backup job should display a warning/error if thats the case.
Unfortunately, we cannot provide technical support through this forum. Please contact our customer support team to have your configuration and restore point removal behavior investigated.