Invalid Timestamps Detected
On iOS devices, console logs display a warning that states
webvr-polyfill: Invalid timestamps detected: Timestamp from devicemotion outside expected range.
No action required.
This is a warning coming from
webvr-polyfill, a dependency of the AFrame/8Frame library. Devicemotion is an event coming from the browser that fires at a regular interval. It indicates the amount of physical force of acceleration the device is receiving at that time. These "Invalid timestamp" messages are a byproduct of iOS's devicemotion implementation where timestamps are sometimes reported out of order.
This is simply a warning, not an error, and can be safely ignored. It does not have any impact on your Web AR experience.