Double-tap message to insert nickname re-appends nickname after every app switch

Steps

Connect to core
In … → Client Settings, under Autocomplete, ensure Double tap to autocomplete is enabled (the default)
Open an IRC channel and load backlog until normal chat messages are visible
- E.g. #quasseldroid
Focus the chat input box
Double tap a message from any user
- E.g. Not-#### the notification bot, or justJanne
Observe the chat input box
Go to the home screen via the Home button/gesture
- Do not use the Back button/gesture as that will destroy the activity
Open Quasseldroid
Observe the chat input box
Optional: keep going to the home screen and returning to Quasseldroid, or switch apps, or lock the screen/unlock
Optional: to workaround the issue, switch to another buffer and back, or use the Back button/gesture to finish the activity

Only one instance of nickname: is visible, e.g. justJanne: .

Every time Quasseldroid regains focus, another instance of nickname is appended, e.g. justJanne: justJanne justJanne.

Tested using Android 10 with Gboard on a Pixel 4 XL.