No, it's not native; it looks like it uses Flutter, which implements its own UI behavior.
IMO, flutter feels even less native than web apps. At least the latter uses system font rendering, supports system-set color palettes (an option in Firefox prefs), supports system preferred keybinds for text editing, system scrollbars, etc.
totally understand, another thing I don't like about Flutter is that it cannot use the system's selection menu when you select text in textfield. All it supports is copy/paste...
IMO, flutter feels even less native than web apps. At least the latter uses system font rendering, supports system-set color palettes (an option in Firefox prefs), supports system preferred keybinds for text editing, system scrollbars, etc.