Does a board have an item limit especially if there are subfolders?
I don’t think so.
Though when having thousands of items it may slow down loading of this board.
However, the more data there is, the bigger the chance you will have some performance issues. We are constantly working on improving this and expanding the number of data that can be added without issues, but it’s a work in progress.
Right now, our recommendation is to have under 10,000 items and 75 attributes in a board to avoid potential issues.