Regular Beeps appear in background of audio file

Hello.
As I said, a regular, faint beep shows up every few seconds in my audio file. One source said it was USB leakage. I have to use an adapter for a microphone; my Mac has only USBC cables.
What could the problem be?

Could be spoiler bleeps added by a free demo version of software, to convince you to pay-up.
[ IIRC some virtual cable software has spoiler sounds on the free demo version ].

Thank you.
I am contacting the only free software I have to let them know my trial period isn’t over.