Cursor leaves the Synced block randomly

Setup and steps (That I had)

1. Page filled with some random text
2. Synced blocks (1 original and one reference on the same page, with some block above and below them) (I had them separated by H1 block in middle too)
3. Use h1 in the synced block
4. Write faster in the h1 synced block fast using characters, spaces.

Result

The cursor leaves the synced block and you will be typing elsewhere.

The behavior is not consistent. Its chances are >1/20