Roon Labs never shared that information. Also not everyone who ran into this issue is using a BBB. I link to oldest related thread I know of for reference:
As your example, documented in this thread, shows, this seems to be a false assumption.
Short brainstorming:
I don’t think I ever seen Roon mention which standard they use for encryption (heck, they even “forget” to mention that internal change at all in the release notes). Maybe they’ve chosen a different standard.
IIRC are various encryption algorithms defined in the TLS standard, some of them optional. As in this case Roon controls both sides of the connection, they may have settled on a …