May times I have been caught where I know there is a node in there somewhere which I need to change, and the only way I can find it is via the config menu. Which is fine in that it confirms the node exists. But not where it is.
What was shown (and marked as the solution) is a great trick I now know and shall use when in the future I need to find a node that way
And yes it is a Tasmota node. Found it. All good with it now.
Not that *that was critical. I realised the problem when I found the node and saw what it was.
What I would do in this case is a bit of a brute force...but export all your flows to a text file, then use a text editor to search, and if necessary, replace. Then re-import. Or, if the text search reveals where that flow is, go back to Node Red and edit it there. If you export in formatted format, you can use the structure to see which tab it's on.
Have a read of this thread - there is a great example in there that i have never thought of before but i intend to rework all my flows)
Put all of your incoming and outgoing MQTT nodes on a single page and have links to and from them on the other pages as required - by looking at the link nodes you will easily be able to see what uses them and where they are - you could also place comment nodes on the individual pages that provide information on this.