Fixed, and thank you - that was a real bug, not you. Clicking away from the window started a second animation loop on every fallback tick, so a minute away left around 1800 of them running at once and the tab locked up. There is exactly one now, and the warning no longer claims you picked up your phone. Reload to get the new build.
Also, genuinely: over a thousand posts of feedback on other people's games is a lot of unpaid work, and it shows. Your report named the exact trigger, which is why it could be fixed the same hour. Thanks for doing that.