Take a look at the “Yesterday / Today / Upcoming” picker right above the list. This is functionally a segmented control, but they did not opt to use the stock style. Instead, they’re making heavy use of the system-provided vibrancy effect.
The default control is blockier and stands out more, which wouldn’t make a ton of sense in this context where it isn’t a super important control.
If you’ve used the new iOS Design Library in Figma and noticed color styles like “Vibrant Secondary Dark,” you’ll see this effect emulated. This isn’t 1:1 with the actual iOS implementation, but it’s a good visualization.
In dark mode, a standard secondary label color is just off-white at 60% opacity. But the vibrant label styles are more complex — they let the background color shine through by stacking multiple fill colors with various blend modes.