Disk space_issue_RHEL_9.0

Dear Community friends,
Greetings! In my Workstation i have RHEL 9.0 along with Windows and Ubuntu i.e treble boot. The Workstation came with Windows 11 and 2 TB disk. At first, I have installed the RHEL 7.0 besides the Windows 11 in the disk and allocated around 860GB (if not mistaken). Later install the Ubuntu on the another disk. Added a 500GB disk besides the 2TB disk.

Recently, i have updated my RHEL 9.0 after long struggle. It is working fine but noticed the Disk space is only 76 GB (30 GB is free) as seen in the screen shot.

Question 1: I have log into Ubuntu 22.04 and taken the screen shot, as seen in the it has 860GB Diskspace. I assume it is the original disk of RHEL 7.0.
Can see some RHEL files in THIS DISK. Seems, my assumption is correct.
In the same time, the DF command and GUI of the disk of RHEL 9.0 shows only 76GB as total disk space. Not sure, what happened? Is it some happen during upgrade to RHEL 9.0? Any thoughts? advise?
Many thanks.

With kind regards,
Chandra