User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:70.0) Gecko/20100101 Firefox/70.0
Steps to reproduce:
Enter some text in an input field on a website (search field at https://startpage.com for example). Try to go back a few characters by using the arrow keys at the bottom of the screen (I believe this is a CyanogenMode/LineageOS specific feature. That feature works as expected in every other app, including the on-board (webview-based) browser app.)
Phone: Nexus 5X
OS: LineageOS 15.1 (aka Android 8.1)
Keyboard: AOSP Keyboard
The cursor keeps jumping back to the end of the current word. Holding down the left arrow key I can finally get it to skip to a prior word.
Using the right arrow key it skips to the end of the current word again, not just a single character.
This behaviour doesn't occur when I disable all next word suggestions/autocorrection in the AOSP keyboard. This is not a usable workaround though.
The arrow keys control the cursor position like the left and right arrow keys do on a physical keyboard.
This works in every other Android app except Firefox.