This bug is still not fixed even in LabVIEW 2025 Q1. But for XNodes I have the solution. Just send FailTransaction reply in a Cancel case in the OnDoubleClick ability of your XNode and that 'dirty dot' never appears! That's exactly what the Timed Loop XNode does. Well, if it's your XNode, you're fine. If not, it means, you have to remove the password and alter the diagram of a NI's node. If that feels not good for you, either leave it as is or wait for NI to add FailTransaction reply to their XNodes.
Similar thread for cross-reference: Xnode Dirty Dot
As to the similar issue with combobox, it looks unrelated to the XNodes behaviour, because in the latter case the asterisk appears only when the dialogue is closed, but when viewing the combobox properties, the asterisk appears right after the dialogue is shown. Needs more investigation, of course. One may start from here: C:\Program Files\National Instruments\LabVIEW 20xx\resource\PropertyPages\Pages\PropPage_RingEditor.vi.
