Notifications from website not grouping Android 15

[gingerbreadbox]

Device: Galaxy S24 Ultra
Model: [SM-S928B]
Software: One UI 7 / Android 15

Issue:
Notifications from the website and the same app are not grouping properly in the notification panel. Some notifications appear as separate entries, while others group as expected. This behavior is inconsistent, other apps group normaly (for example: Telegram, Gmail, etc.).

I have already checked the following:

• "Allow notification grouping" is enabled in app settings.
• No special notification channels are used or silenced.
• Tried clearing cache/data and reinstalling the app.
• Behavior persists after reboot and is not affected by Do Not Disturb or Focus Mode.
  
  Expected behavior:
  Notifications from the same app should appear grouped by default, with the ability to expand/collapse them.

Thank you.