You can test exactly what the recipient will see by emailing yourself via simplelogin
Did that email go directly to the recipient address, or did it go thru a simplelogin alias for the recipient address? The simplelogin recipient alias strips off your real email address during the pass thru.
answering the question in the title...no. Not to the service you're using it to sign up for anyway
But someone monitoring the emails going from one address to another? Probably yes.
Proton
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SimpleLogin lets you send and receive emails anonymously via easily-generated unique email aliases.