Tonight was update night, so I crossed my fingers and installed the 22H2 update for Windows 11.
And, somewhere during that installation, it "automatically" updated my AMD RX 6700XT driver to one dated July 25, 2022, and promptly re-introduced the color bug in Vegas 19. This also broke the AMD Adrenalin control panel, which claimed my driver was incompatible.
So, re-installed 22.5.1 and everything seems to be back to normal.