Hi @MAlgoul2000 , thank you for your post.
I have searched my inbox and cannot locate the words 'Message sent via Microsoft Flow, enabling you to create automated workflows between your favorite apps and services.' in any email related to a notification or an approval in the last few months.
With most of my emails I tend to specify the send from using the following method (or similar). 
Whilst I am not certain this is the complete solution I'd ask for you to give that a try and specify a "From (send as)" where possible and see if it resolves it for you.
Also, in terms of approvals, I am wondering if you have tried a few diferent templates to see if the generate this. I have just used:
No sign of any unwanted wording.
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Any other questions, just ask.
Thanks, Alan