Deleting files using the File manager

Good afternoon! I have an unusual situation going on. When deleting a folder from the left side of the file manager (screenshot 2), the system writes that the folder has been deleted, but after refreshing the page, the folder appears along with the files.

screenshot 1:

screenshot 2:

If I delete a folder from the right side of the interface, it is deleted without problems, along with the files.

I made a copy of my database and wanted to save it as a template. I deleted all records from the database except one (I want to use it for a training example). Then I chose “Export” and the system wrote that the database volume exceeds 100 MB.
After that, I found out that when deleting lines, all files remain in the database.

My first question arose - how long are the files stored in the database after being deleted from the table?
And the second question (fear), if I delete files in the new database, they are not related to the original database in any way? Is everything saved in the source database?