Gitlab repo size

We have installed an On premis gitlab (ce 16.8).Some of the projects of application teams are seen are showing large size in the Admin Area >Projects >sort by project size
approximately 1 GB but while checking the repository ,it does not have any big files like node_modules,When downloaded ,it shows only 3 MB.
Any Idea on this?

Git stores all previous versions of all files that have ever been in the repository, so perhaps the project has contained some big files?

how to find and delete from ui

That would break some of the git functionality, so I don’t think it is possible.

Check that in your project use the Git LFS to store the large file. it allow to store file outside the repository. To see these files you have to use the LFS command to see the files.