Purely out of interest, I would like to submit the following question to the forum. It is not a problem, everything works fine.
This morning I was offered a stable update for my Firefox with version 96.0.3-0.1, which I installed immediately. Since I regularly check under Branch Compare which program versions are available, I discovered that three versions are currently listed for Firefox 96.0.3.
They are simply patch-level differences. The version in Testing has a slightly newer patch than the one in Stable, and considering that the patch levels in both Stable and Testing are still at 0.x, those two appear to be preliminary patches ─ possibly a small bug fix ─ for the definitive patch applied to the version in Unstable.