Loaded a Rufus stick with 24H2 and tried starting it in an old 2007(?)Q6600 Dell and it would sit with W11 symbol up for a while and then reboot. No message, nothing.
Put one in with 23H2 and it started the install just fine.
Think they did something that is messing with Rufus. Maybe a Rufus update will fix that IDK.
Nothing to do with Rufus. Microsoft has just plugged a hole. The officially supported CPUs (and some of the newer unsupported ones) have some instruction set coded into them. (You can find articles that identify what this is.) Release 24H2 looks for this instruction and, if it's not there, the system won't boot.
There are hints that Rufus may be able to patch this, but I wouldn't count on it. Even if they dom, Microsoft is obviously now aware that people are doing work-arounds, and MS will find a new way to sabotage this.