Motion title: not visible diff in change reco

Describe the bug
If a user creates a change reco on a motion title it can happen that the diff will be not visible in the motion text. The text of the change reco won't show it.

I guess the motion text length has some influence on it.

Example - compare titel and change reco

How to Reproduce

1. open a meeting
2. open motion and create a motion with the title and text below
3. open the motion > create change reco on title by deleting the first two word > diff not visible

Title
Eine wunderbare Heiterkeit hat meine ganze Seele eingenommen, gleich den süßen Frühlingsmorgen

Motion text
Wenn das liebe Tal um mich dampft, und die hohe Sonne an der Oberfläche der undurchdringlichen Finsternis meines Waldes ruht, und nur einzelne Strahlen sich in das innere Heiligtum stehlen, ich dann im hohen Grase am fallenden Bache liege, und näher an der Erde tausend mannigfaltige Gräschen mir merkwürdig werden.

Expected behavior
The diff of the title should be correctly displayed.

Additional information
Issue is linked to #2956

Reproduce the change recommendation from a motion title using the supplied long title and motion text, then trace the frontend rendering path for the title and motion-text diffs. Compare both diff displays and verify that deleting the first two title words produces a visible title diff without changing the motion text diff behavior.