[com.wetter.androidclient] Premium subscription silently fails

**Affected app**
Name: weather24: Forcecast & Radar
Package id: com.wetter.androidclient

**Describe the bug**
Subscribing to premium version fails without error. The app shows correct yearly and monthly billing options and pressing subscribe now opens a pane at the bottom where the billing method can be selected. When tapping "Buy" the pane disappears, no errors are shown and the app shows the subscription options again.

**To Reproduce**
1. Fresh installation of app
2. Select "Subscribe to PREMIUM" in the Welcome! screen
3. Click "Subscribe now"
4. Click "Buy"

**Expected behavior**
Successful subscription to PREMIUM version.

**Screenshots**
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**System**
Android Version: 16
Custom ROM: CalyxOS 7.2.2.0

**microG**
microG Core version: 0.3.15.250932-23 (6a7d640)
microG Self-Check results: All ticked

**Additional context**

[redacted_logcat.txt](https://github.com/user-attachments/files/29905615/redacted_logcat.txt)

Start by reviewing the attached redacted_logcat.txt alongside the reported Android 16 and microG 0.3.15.250932-23 environment, then trace the subscription flow reached after tapping “Buy.” Done means identifying why the purchase silently returns to the subscription options and ensuring a successful PREMIUM subscription or a visible error.

Written by the indexing model from the issue text.