Maybe a bug:after exporting the mobile prototype, previewing it in the browser will cause a flash of position moving instantly

Hello everyone, when I use a custom size, such as 375*667, to design the interface prototype and export the HTML file. When accessing the exported index.html in the browser, the page should be directly centered. However, now it will start from the left side of the screen and be instantly centered. For details, see the loom screen recording: https://www.loom.com/share/a4f4008e497546d69660f0cbb01ef4be?sid=396acd8b-675b-4a37-9273-ec390e31a14a

I want to know, is this a bug in Axure or a problem with my settings?
(My operating system is Windows 11, and my Axure version is 10.0.0.3924)

“demo.rp” is the original file:
demo.rp (46.0 KB)