After getting an input about this from @DMehaffy in Strapi discord channel, if you’re using the upload plugin (any provider) to upload multiple files, they aren’t properly purged from /tmp folder, which can lead to the high disk storage usage.
Until the bug is solved, you can use a cron job to delete the files inside /tmp that are no longer needed.
One more thing, the recommended settings for the server is
“Minimum required storage space recommended by your OS or 32 GB of free space” based on Strapi docs.