Issue:
In game you can place pieces accurately with taps only if the page is scrolled to the very top. It seems the overlay for where you placed a piece no longer scrolls with the board, so if you scroll down the page slightly, it now places pieces significantly above where you tap.
Ah, this is the problem I’m having on iPhone 6 too with safari. I thought it was something weird to do with my phone orientation rotating the page and I only noticed it in analysis mode, but after reading your post I realised you’re right it’s to do with the page being scrolled! Thanks for pointing this out