Microsoft has had the registry keys for Run and RunOnce in the registry since the registry was introduced in Windows 95 and Windows NT 4. But in the 20+ years that those keys have been there (and I’ve used them for a variety of things) I’ve never known that there was a limit on the length of the commands that you could put into those keys.
I found this while working on a client project when I needed to kick off some powershell automatically when the server restarted to get it added to the domain, as well as do a few other things. But for some reason the key just wasn’t running.
The limit does seem a bit short, though at least it’s one longer than the max length of a file path.