125GB disk. What does it contain? How to empty it?

I have a shutdown IPFire virtual machine that I want to save to move to a new server.

The backup program shows me space for 125GB, I can’t understand what the reason could be.
What could have generated all these GB?

I can’t activate it because there is another firewall with the same addresses and they would conflict while I am working remotely.
I’ll have to go get it with an external disk, but I would like to understand what could have happened.

Is this the IPFire backup program at the IPFire menu System > Backup?

If yes, then you can use this to find large files bigger than 10 MB.

tar tvf /var/ipfire/backup/2023-09-09-16:15.ipf | awk '$3 >= 10485760 {print $3"\t"$6}' | sort -t' ' -k1,1nr

change the 2023-09-09-16:15.ipf to your recent backup.

EDIT: found here

No, it’s not that.
Maybe it’s the Squid cache and update accelerator

The suggestion was to run the tar command on your IPFIre backup file that is 128GB large to get a list of the large file or files that are using such a large amount of space.

The link provided by @jon was to explain the background behind the tar command that he provided.