Can you provide a screenshot of your Send an Email definition? It looks like something is trying to use a connection that's not available.
OK, can you show the formulas being used for the message and the subject?
It all looks like it should work. Since there are only three calculated values I guess I would suggest replacing them with hard coded values temporarily to isolate which one is causing the issue. Nothing really jumps out at me as being wrong.
Then I would remove the send an email action, save the flow, close Power Automate and the browser, re-open and try to add a new Send an email. Something in the definition of the connector is evidently corrupt.
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