WASM: Gray screen flashes before the main window showed

In the previous WASM platforms (such as 6.5.3), I set a background color in the HTML, for example, #000000, and then I also set the same background color in the QML Window. As a result, this WASM webpage would remain black from the moment it was opened until the program loaded successfully.

However, in version 6.8.0 Beta3, with the same code, a gray background flashes. This seems to occur in the process between the successful loading of the xxx.wasm file and the display of the main program window. The gray flash only lasts for a short time, roughly between 100ms and a few hundred ms. I tested the simplest QML program, and I could still see this gray flash, which results in a flicker during the loading process, making the loading process feel unnatural.