I experienced a similar problem. I use IntersectionObserver for infinite scroll. I tested it out on many different devices and browsers including MacOS, Linux and Windows devices with Chrome, Safari, Opera, and Edge browsers. I never experienced an error, neither my customers.

However, a week ago a customer stated that scroll is not working on any devices of them. We had online sessions to find the issue, we tried different browsers, etc. The interesting thing, it was working time to time. Then I noticed that I set threshold to 1 without even thinking what it means. (It was actually a snippet of AI generated code) Setting it to a lower value solved the problem.

In short, I believe threshold value may not be very precisely deterministic on different devices/browsers. It may even sometimes work and sometimes not with exactly the same configuration. So, assigning it to a lower value may save you.