[com.ubs.Paymit.android] Heavy graphical flickering in UBS Twint app, inputs not registered reliably

Affected app
Name: UBS Twint
Package id: com.ubs.Paymit.android

Describe the bug
The app heavily flickers from startup : the displayed graphics get shown and then redrawn very often, which appears to cause lag. This flickering affects the top bar too, and inputs are not reliably registered.

I tried downloading and running another Twint app (the Raiffeisen Twint app) and this issue did not appear.

The issue did not appear in previous versions either, I have used the UBS Twint app for months at a time with no issue.

To Reproduce
Steps to reproduce the behavior:

1. Open the UBS Twint app.

Expected behavior
The screen does not flicker, and the inputs are responsive.

Screenshots
Video of the issue. Sadly Twint does not allow screen recording, so I had to make this scuffed video instead. The quality is not good but the issue is visible. You can see I have trouble typing in the digits.

System
Android Version: 13
Custom ROM: /e/os 2.4.1-t-20241009439851-official-FP4 (The problem did occur on the latest stable version too. Here, I tried the unstable one, but no luck.)

microG
microG Core version: 0.3.2.240913-22 (43f9740)
microG Self-Check results: All ticked

Additional context
This might be an /e/os issue and not a micro-g one, but in doubt I still posted here. Thank you for your help!

No source file, test, or entry point is identified. Start by reproducing the startup flickering and unreliable input with UBS Twint on Android 13, using the reported microG and /e/OS versions; done requires isolating whether the cause is in GmsCore or the surrounding system and confirming responsive, non-flickering input.