When MacOS is set to light mode, the background of the browser remains dark, but the text becomes dark also, unlike in dark mode where the text is light. This make the text illegible due to the very low contrast.
MacOS set to light mode:

MacOS set to dark mode:

The background should become light to match the light mode setting and the darkened text.
Alternatively, the background could just stay dark, if a light mode is not developed yet, but the text should stay light so it is more legible.
Version 0.99.137-beta (WebKit 623.1.8.0.0) Build date October 24, 2025 MacBook Pro (macOS Tahoe 26.0.1 build 25A362)
Tahoe (26)