Can GUP+11.0 RU5 provide update for client+12.1 RU1 MP1?

Does anyone know GUP with 11.0 RU5 can provide update to client with 12.1 RU1 MP1?

I thought GUP cannot provide pattern file to 12.1 client. but my 12.1 RU1 client log showing download from GUP with 11.0 RU5.

on System log of Client management says

"Downloaded new content update from Group Update Provider successfully"

Sylink log also shows access to GUP port 2967.

so I expected Client 12.1 RU1 will request pattern file to SEPM.

or am I misundastanding the log?

Thank