In response to this, I read the spec of setTimeout, bu I couldn't find the part where implementations may have an upper bound. Can someone more familiär with the specs point me in the right direction?
Adding a comment here to check back later because I'm curious now if someone has the answer. I thought it would be easy to find the answer, but I can't find it either. I figured it would say somewhere a number is converted to an int32, but instead I got to the part where there's a map of active timers[1] with the time stored as a double[2] without seeing a clear loss happening anywhere before that.
[1] https://html.spec.whatwg.org/multipage/timers-and-user-promp...
[2] https://w3c.github.io/hr-time/#dom-domhighrestimestamp