The Opera version doesn't match the Chromium version, causing the wrong driver to be downloaded
Opera version 122 is actually using Chromium 138, as seen in the screenshot. The chromedriver that was automatically downloaded for it has version 122, but it should be version 138, because the driver version should match the chromium version in this case (not the browser version).
It would be a lot more convenient if the version of chromium-based browsers actually matched the version of chromium that they use. If I can't easily get the chromium version of the Opera browser from a command-line call, then I'll have to build in a workaround for it.