After recent update of MacOS to version 26.3.1 (25D2128) ALL of my files were moved online, although only a part of them are marked as online only in my prefernces. Moreover, if I specifically ask to make a folder that is supposed to be offline to be available offline only the files in the folder become available offline. All the embedded folders remain online only.
I'm using Dropbox version 244.4.6580 on Mac Pro Apple M2.