Well the newer firmware could handle both revs of course, but our image was built on the older firmware which knew nothing of this newfangled 1.4 tin.
And the new firmware only came with a new kernel, and new userland software stack that was incompatible with our driver and application, so we had to knife'n'fork the new firmware into the image as the least worst solution.
And, whats even more annoying, was that we'd done a bulk order for the Pi3B+ to avoid this sort of thing, but half the delivery was delayed by 12 months over the pandemic parts shortage.
End moan :)