Dictionary Shortcut Behaviour in Mail

I have macOS Ventura 13.2 installed with latest updates.

I often look up words in the Dictionary using either the "force click with one finger on a word" or the Shortcut Control+Command+D on a highlighted word.

Whilst composing a message in Mail, the above shortcut also works. However, when reading a message the shortcut does not work while the "force click with one finger on a word" does work.

Is there any setting in Mail which overrides the expected behaviour of Control+Command+D (Look Up in Dictionary)?

In System Settings ...

... there was no shortcut set in the Searching Service for "Look Up in Dictionary".

When I set up the service with the keyboard shortcut Control+Command+D this does not work in the Mail reading mode.