It only shows that the marketing, that was concentrating on Gears being an essential gamepass game, was effective and by this it was the first AAA game from MS that was marketed in that way.
Actually it wasn't the first, Crackdown 3 was also marketed in a similar way, and that did really poorly sales wise.
In the past the argument has always been that Game Pass adds to retail/etail sales, but I think Gears 5 and now Crackdown 3 (the two most recent tentpole Microsoft first party releases) point to the opposite potentially being true (at least with AAA or tentpole titles), in that actual sales wise, Gears 5 is looking to possibly show a notable decline in launch sales versus Gears 4 (due to GP), which already showed a huge decline in launch numbers versus Gears 3.
And without numbers, I'm not sure how effective I'd call the marketing given Game Pass according to Spencer already had "
millions" of subscribers, and Gears 5' first week player numbers were 3 million (which would include sold copies, game pass users, shared accounts, multiple accounts, grey market, used etc) despite all the marketing and Game Pass offers, which essentially gave the game away for free.
The player numbers for the first week are actually lower than the actual sales of Gears 3 in the same time frame. Lest we forget historically Gears has been Microsoft's third biggest IP, behind only Minecraft and Halo.