Hi Zed,
I have actually seen the same behaviour on your theme demo site. I have seen this with IOS 14.5 and 14.6 beta as well as with the latest (and also previous) Catalina release.
I just took a screenshot with my IOS 14.6 device, however cannot attach to this reply. If I should send this to your info@ address let me know please. I hope it helps you to narrow this down.