I think it depends on if you can even suss out a problem.
Mine was early, and when I have it on zone Af, and servo, I can't catch a bird flying towards me to save my life.
However, when I use one AF point in servo, I can follow cars and horses and get sharp images just fine. (***ive turned off all non cross points)
If you have ordered from someone reputable, then just test the crap out of it and use a zone setting with ai servo and see how you get along with it during your return period. Plenty 7D2's are stellar out there in the field.
I'd like to think I have a 'bad' one, but as I dont' rely on zone AF servo for 99 percent of my stuff, I'm not too worried about it, and it could still be the idiot camera operator (me). Long learning curve with all the cases, but just start with it the way it is out of the box - twiddling with the case modes will probably add variables to trying to figure out if it is the camera or you.
At any rate, I don't use it for birding, so I'm ok with this 'glitch' and someday I'll really hammer at it when I find someone I can talk to and test in real time. But I don't see the need to send back the camera when it does 99% of my needs just fine. However, if you need it to do zone af servo and be tack sharp, then by all means, send it back if it doesn't meet your needs.
On the older 7D... may try cleaning where the af sensors are at, to see if you have dirt covering them, if the insides are dirty.. I've heard that can be part of it, also lenses can start to fail and that maybe the issue, need to try some different lenses on it.
Godox/Flashpoint r2 system, plus some canon stuff.