Hello @angel_rrm ,
I don't know if it's the ideal solution, but it works for me. The following process is built searching for the "regards" word, it has to be replicated for "thanks".
I'd to highlight that if you're receiving an email containing "regards" or "thanks" many time, it won't work.
1. Add an "HTML to text" action providing the email body from the Trigger:

2. Add a "Compose" action where putting the following expression:
length(body('Html_to_text'))

3. Add a "Find text position" action providing "regards," in the "Search text":

4. Add a "Compose" action putting the following expression:
substring(body('Html_to_text'),body('Find_text_position'),8)

5. Add another "Find text position" action:
- Text: outputs from previous Compose action;
- Search Text: ,

6. Add a "Compose" action putting the following expression:
add(body('Find_text_position'),body('Find_text_position_2'))

7. Add a "Compose" action putting the following expression:
substring(body('Html_to_text'), outputs('Compose-AddNumbers'), sub(outputs('Compose-TotLength'), outputs('Compose-AddNumbers')))

8. Add a "Compose" action putting the following expression:
replace(outputs('Compose-GetName'), ',', '')

Here the flow:

Here the output:

Please let me know if the issue is fixed.
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BR,
Marco