I think the "high downforce engine cover" thing is a red herring. The original launch spec engine cover with the cannons was in use all year long (including Monaco, Barcelona) until Hungary where they started calling it a "low downforce" engine cover and we got a story about their being 2 different engine cover specs (something that neither of Mclaren or Ferrari have needed in their cars which are faster than the Red Bull with 1 engine cover all year...)
So I think it's more likely that the old engine cover was just a bad part which is why it has been abandoned. Mercedes also abandoned that cannon design last year... Keep in mind that the current "high downforce" engine cover is the engine cover that was used on the RB18 and the RB19 which were very efficient cars but now we're being told it's a "draggy high downforce engine cover"? Is that not suspicious? The "two engine cover" thing sounds more like a PR operation. The were probably just experimenting and realized the original design from last year is better so we'll never seen the cannons again (but let's wait until Saturday to confirm that...)