Glad that you've come out of the shadows to ask a question!

A codeshare is always another airline's flight. That is the essence of codesharing. One airline puts its own code on another carrier's operations. In this case CO8243 was always VS0023. The difference is who you pay for the ticket and then there is a bunch of behind the scenes stuff between the airlines to determine how they split the revenue.

From a baggage perspective you are always subject to the rules of the carrier to which you submit your baggage initially. That is the case regardless of the code you are traveling on. So the baggage rules haven't changed for you. The (slightly) bad news is that you have always been subject to the VS rules for economy travel as a non-status passenger. Be ready for very stringent limitations on your carry-on, among other things.

Regarding you earning EQMs, so long as the flight continues to hold a CO code on it you will earn EQMs. This is a "bug" in the CO systems that issue such credit and one that they have previously stated they have no intention of fixing it. Looking at the schedule out into January at least right now VS23/24 still carry CO codes so you should be OK.