MBS plugins message?

An iOS app I have in the app store has people complaining that it throws up a message to say MBS plugins are being used before registering.

However, having searched the source code, there is no reference to ‘MBS’ anywhere in it.
Anyone know why this might be happening?

When I look at the compiled app, and ‘show contents’, there isnt a folder of plugins like there would be for a windows app.

image

well, this looks like something from MBS Picture Plugin is used.

https://www.monkeybreadsoftware.net/pluginpart-picturecopy.shtml

I have discovered that I have several versions of the source, and did leave a test call in place.
My fault.