There is no such thing as a "pmCO 763." All 763s are sUA. Your flight has always been an sUA flight, as reflected by the flight number (UA985). It's simply an aircraft swap.

Nice score on the front cabin. Who cares if it's BF service? There's no meaningful difference.

"pmCO" is not the right terminology, either; when you're referring to the operating subsidiary, it's sCO and sUA.