Delayed typing with external keyboard

ONLYOFFICE Mobile: Documents
Do you want to: Report a bug
Device: Samsung Galaxy Tab S6 Lite
OS version: LineageOS 21
App version: 8.2.0
Mode: On Device
Additional information: Bluetooth Keyboard Case Targus GP-FBP615T

Hello,

I have a problem with Onlyoffice and my Bluetooth keyboard.
When I write something with the keyboard, it always takes one or two seconds for the letter to appear on the monitor.
Typing quickly is impossible…
In addition, the virtual keyboard always appears, even if it is switched off in the settings.
This only happens with Onlyoffice, otherwise in no other app and I have also tried it on another mobile phone, exactly the same problem, only with Onlyoffice.
What could be the reason?

Thanks for the help
Daniel