Have an honest conversation with your dealer about the situation. Sure they may not have any clue about yours but if that's the case, I'd ask if they could find out some info...ask a regional rep, ask GM, see if they can give you an answer other than...you'll get it someday.
During that conversation ask about the possibility of ordering a 23...granted we don't know if you put down a deposit or if this is your first time buying from them or if you've bought 20 vehicles from them...but if they balk at ordering a 23, don't burn the bridge on the 22, but reach out to another dealer about ordering a 23.
They'll probably want to keep you as the buyer for the 22 because even though they shouldn't have any issues selling it, there may be a point where it's delayed enough that other buyers would question why a 22 is arriving so late into the 23 build year.
As far as exactly what may be holding yours up, ultimately it doesn't matter as it's not like GM or you dealer is going to do anything about it. No rhyme or reason for when the 99.9% completed vehicles get the final .1%...
Probably the only benefit of staying with the 22 is that I'd expect the MSRP to be a couple grand cheaper than a 23
8 month wait for something built in Feb is a little much...most of the ones "stuck" in Midlothian were built in late March-June...there have been several examples of 23 Tahoes being ordered/accepted/built/delivered in 30-45 days, which although it isn't the normal ordering timeframe, there have been enough of them to say the builds are moving quicker