Well....it's impossible to answer that question. The Inspire doesn't have "Z3 firmware" per-se. The Inspire has its OWN firmware, as does the Z3. That said, the Z3 had the latest firmware, and the Inspire has v1.08. Because DJI doesn't really publish any real data regarding FW versions, I can only speculate that the drone FW is drone-specific, and the camera FW is camera-specific. In other words, I'm pretty sure drone FW doesn't affect the camera's ability to focus. But who the hell knows? If you talk to any DJI lemming, they will INSIST that you have to have the latest versions of all FW and software, even at the peril of the drone. They have literally zero experience, and merely read from a script. So I would NOT invest too much confidence in what they purport. That said...
My neighbor said he experienced some of the same softness issues I experienced, but I haven't seen his photos.
It would be interesting to see what others are experiencing. If available, I would like to see full zoom Z3 photos from some of the other users.