Keeps asking for PGP password despite "remember until cleared"

Checklist

• I have used the search function to see if someone else has already submitted the same bug report.
• I will describe the problem with as much detail as possible.

App

Thunderbird for Android

App version

10.0

Where did you get the app from?

F-Droid

Android version

15 (GrapheneOS)

Device model

Pixel 8

Steps to reproduce

1. Connect account in Thunderbird with OpenKeychain for PGP end-to-end encryption
2. Try to decrypt an email in the inbox
3. Enter PGP password (for private key) when prompted and keep it as "remember until cleared"
4. Wait an unknown amount of time, I'd say a couple of days in my case
5. Try to decrypt another email
6. It asks for the password AGAIN!

Expected behavior

When I say "remember until cleared" I will never have to enter this password again.

Actual behavior

It keeps asking for the password - not every time, but once in a while.

There's also this thread in the K9 forum from another person without any answers so I'm not the only one

Logs

No response

No source files or tests are named. Start by reproducing the password-cache behavior with Thunderbird for Android 10.0, OpenKeychain, and the stated Android setup, then trace the PGP password handling from the decryption flow. Done means that choosing “remember until cleared” prevents later prompts until the cache is explicitly cleared.