Hello Everyone,
Our University is using Moodle 3.5 and Moodle data file and database is growing so fast. Currently, our Moodle data is 1.5 TB. According to analytics, its daily usage is 1 GB. On top of that recently 3 GB has been used over the weekend. Being the site administrator it is really hard for me.
Moodle is growing fast? That is a good thing!

Seriously, the question is whether the growth is genuine or caused by an error. Genuine growth is users uploading more files. Errors situations are many, processes breaking leaving junk uncleared, for example. There is also a gray area. Like users taking backups and leaving them in the course. The next backup, could be an automated backup, taking backups of those backups!
You should investigate. This means system level access. An easy starting point could be the additional plug-in https://moodle.org/plugins/report_coursesize.
Seriously, the question is whether the growth is genuine or caused by an error. Genuine growth is users uploading more files. Errors situations are many, processes breaking leaving junk uncleared, for example. There is also a gray area. Like users taking backups and leaving them in the course. The next backup, could be an automated backup, taking backups of those backups!
You should investigate. This means system level access. An easy starting point could be the additional plug-in https://moodle.org/plugins/report_coursesize.