Disk usage isn’t changing or reducing

When I delete files disk usage isn’t changing or reducing.
I also am not able to update to latest version.

Are they still in the trash?

Ok, in that case perhaps you could fill out the support template and explain your problem in some detail.

You can look in your file system under /path/to/nextcloud/data/username and search the folders. Maybe you find the solution for the files. Maybe for some reason the value was not updated and you have to wait. (e.g. Cron?)

If you can’t find the error:

You can also rescan the files:
sudo -u www-data php /path/to/nextcloud/occ files:scan --all