We have existing macros that is not yet compatible with the new editor.
While we’re working on making them compatible, we’d like to know if the macros are being rendered on the new editor so we could render a message informing our users on the incompatibility and upcoming support.
Is there a way we can detect if the macros are being rendered or inserted into the new editor, programmatically? If so, how?
Well, with the new editor Atlassian wants macros to look the same in both edit and view mode. The easiest way to achieve this is to simply let macros think that they’re in view mode.
So I suspect that detecting edit mode in the new editor isn’t possible - though I’d be happy to be proven wrong. 
Edit: I guess a place where could let your users know about this would probably be a custom macro editor.
Thanks @sven.schatter.
We intend to convey this message in both edit(via the custom macro editor) and view mode but only in the new editor as the macro is functioning just fine in the old editor.
Do you know if there’s some kind of a flag in the new editor that we can use to check before rendering this message?
We would also love a flag for this and have requested it on some related conf cloud issues. To my knowledge it is not coming and not planned but would be happy to learn otherwise. The change in ux by the new editor creates some need to behave differently depending on what editor is in play.