Copyright laws differ in different countries and I'm not a lawyer. Having said that,

I wonder what that other song is? Could it be another song generated by BIAB, and it happens to be such an exact match that it triggered the warning?

Do your chords have any rhythmic patterns (shots, holds, rests) that would make it sound like 'hits' in the song that are distinctive and recognizable?

In theory, without using someone's melody, you should be OK, unless you copy the 'hits'.

However, the problem may be that you said the word "demo". If this is a PG Music demo song, then those ARE copyrighted.

This is the sort of case that they ask juries to untangle, when big money is involved. It's not an exact science (yet).

BIAB 2025 Win Audiophile. Software: Studio One 7 Pro, Swam horns, Acoustica-7, Notion 6, Song Master Pro, Win 11 Home. Hardware: Intel i9, 32 Gb; Roland Integra-7, Presonus 192 & Faderport 8, Royer 121, Adam Sub8 & Neumann 120 monitors.