Database size won't shrink in finder after deleting files

In Finder, the .dtbase2 file remains of the same size.

As has been discussed before, the size of a database in File > Database Properties is not the same as the size of the database file in the Finder.

The database in the Finder contains more than just your files. It also includes metadata and the searchable indices for the database. That can take plenty of space, especially if a database has a lot of textual content in it.
Also, and a very likely contributor, there are two rotating backups inside the database allowing you to roll back the metadata up to two weeks ago.

Here, the current metadata and backup metadata comprise ~1GB of this 3.3GB database…

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So I would find nothing surprising about your current situation with such a massive amount of data in play.

And yes, did you empty the database’s Trash?