The desktop gained a pane color so the window’s glass shows through the composer and the messages you send. The script that turns the desktop themes into iOS colors refuses any new color until someone carries it across on purpose, so it had stopped running and the iOS colors had fallen behind every theme change since.

It now carries the pane color across, and the iOS colors are regenerated from the current themes. The iOS app has no composer, sent messages or window glass, and its cards come from extensions, which use the regular surface color on both platforms, so iOS keeps the surface color for its cards.

Catching up does change how the Liquid Glass themes look on iOS: extension cards are opaque, secondary text is stronger and the main buttons are blue, as on the desktop.

Evidence

No screenshot: No iOS screen draws with the new pane color. The Liquid Glass themes do look different on iOS, catching up with the desktop (opaque extension cards, stronger secondary text, blue primary buttons), but the iOS app was not built for screenshots.