[Bug/UI] Font inconsistency in Chinese locales on Android 16 / OxygenOS 16

[SoknyArtemis]

Hi there ! First of all, thank you so much for developing Daily You. It’s a wonderful app and I’ve really been enjoying using it !

I’m writing to report a font rendering issue I encountered, which seems to behave differently depending on the app's language setting.

The Bug

I noticed that the font style changes inconsistently when I switch languages within the app:

• Traditional Chinese (繁體中文): The UI immediately switches to a Serif (Songti/Mingti) font.
• Simplified Chinese (简体中文): The font stays Sans-serif, but it becomes much thinner than my system default (it looks like a light variant).

Further Observations

After some testing, I found that this behavior completely ignores the system-wide settings. No matter what I change in the system language, region, or global font settings (I use a built-in Roboto/Sans-serif), the app strictly follows its own internal language toggle:

• The Serif font appears only when the app's internal language is set to Traditional Chinese.
• I've already tried clearing all app data/cache and performing a clean re-install, but the issue persists.

My Thoughts

I'm using OxygenOS 16 (Android 16), and I noticed this system version includes a built-in Serif font. I'm not a developer, but I suspect the app (or the underlying framework) might be automatically picking up this built-in Serif font for the Traditional Chinese locale, bypassing the actual system-wide Sans-serif choice.

Would it be possible to look into this ? I’d love to have the UI stay consistent and unified with my system's Sans-serif font across all Chinese locales.

Environment Information

• App Version: 2.17.2
• OS Version: Android 16
• Distribution: OxygenOS 16
• System Font: Built-in Roboto (Sans-serif)

Thanks again for your hard work and for such a great open-source project !

📸 Click to view Comparison Screenshots

Traditional Chinese (Serif)	Simplified Chinese (Thin)

[Demizo]

It appears this is a Flutter issue, see flutter/flutter#178533. This will be fixed when it is rolled into a Flutter release. Sadly, I likely can't do anything about it until then.