Hello
I use Files App from time to time to find my files, pictures, alike.
I never use Search function though.
So when I open the app it looks more or less like below (picture attached), I can see items categorised.
Now I can mainly try guessing how the search function works, see the second picture. It might be based on my recent searches or on more generic categories, in my case it does not suggest any files only provides me with these categories.
I am not sure why the option last week doesn’t show everything you did but again, it’s a reasonable guess, it is only the search function suggestions, it is not the actual content of your files.
Good luck
