> The vanilla launcher will automatically patch 1.12 to 1.18

The patch seems to have been to the client-1.12.xml file, which I believe is the log4j configuration file for all client releases since 1.12, and the change seems to have been to add a {nolookups} flag to the log format (but I don't have an old copy of that file to compare and see if anything else was changed).

If I'm not wrong, this gives a simple way to make sure your copy of Minecraft is patched: just check if that file has that {nolookups} flag.

This will be a pain for MC speedrunning where older versions are still quite popular AFAIK.

Thanks, this is the first message where I see the full instruction on where and how to apply the workaround. I was not even sure if this is something I should change in the third-party code that I run in a Docker container, and now I know it is just a change of the ENTRYPOINT or CMD line.