domain – Email “FROM address” is changed to an unexpected email address

I have enabled DMARC settings in my domain ( Now when I send emails from my email address ( to email lists or email groups, I can see that the email’s from address and to address become identical. can someone please tell me why this is happening? because of this sometimes my emails are now being sent into spam directory also.
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but when I remove DMARC settings from, everything goes back to normal and I can send emails to email groups without any problems.