Backspace incorrectly places caret before linebreak when deleting the last character of a line

[MrJul]

Describe the bug

The following video is a single Backspace key press followed by an Enter key press:

input.mp4

Notice that backspace deletes 'b' and moves the caret to the line before. Only 'b' should be deleted, and the caret moved at the start of the current line.

To Reproduce

Delete the last character of a line in a multi-line textbox.

Expected behavior

The caret should stay on the current line.

Avalonia version

master 228ecc5

OS

No response

Additional context

Caused by #16135