Hmmm… my iPhone has a steady stream of notches at 200ms on WiFi (nominally 20ms) and cellular (nominally 50ms). The pacing is at ~1cm intervals on my screen. I wonder if it’s on my end or on the website.
When I used ping to test my iPhone's wifi latency (1), I frequently saw 200ms results, even when the phone screen was on and I was using an app. Maybe there's aggressive power saving stuff causing latency on the network stack. I was very surprised as well. Friends with Google Pixel phones tried a similar test on their Wi-Fi networks and got similar results.
Edited to add: When I test with the Blip website, it never goes above 80ms for gstatic. Go figure.
1. Tested by a wired Mac pinging the default gateway, a Google Nest Wi-Fi Router, which was <1ms consistently, then I used the wired Mac to ping the phone