I have a folder, it displays the default Opus columns. I have a sub-folder of that folder, which adds one column (user description). If I open the subfolder and do nothing, before returning to the parent folder, there is no problem. If I open the sub-folder, click on the user description column to sort by it, and then return to the parent folder, I find that the parent folder - and all sub-folders - now have that new column. As stated, as long as I don't interact with the user description column when I go into the sub-folder, there is no issue. Bug? If not, how do I stop Opus from doing this?
What you're seeing sounds like what is described in Folder Formats: Detailed Guide, part 8: Temporary Formats.
Right-click the format lock icon on the status bar, then choose Reset to folder's format to reset the window back to normal. (Also available via the Folder menu if you prefer.)