"Save as ..." in Microsoft Office always brings up "Documents" folder in Finder "Save as ..." ignores the location of the current file and ignores the last save location. This means I have to navigate back to the original files source folder every time I want to save a different version of the file in Excel.
Many apps do this. Years ago a utility was released called DefaultFolderX. It lets you fix this problem for all apps, and it can even store two different locations- one for opening files, one for saving files. It’s excellent for when you open files from one directory, work on them and save them into another directory.

It is unlikely that Microsoft will do anything about this function as they would regard it as the operating system’s responsibility.