Just a heads up as of 1/18/2024:
I sent an original copy of my birth certificate along with a photocopy of the birth certificate. I received them both back along with a copy of first page of the I-129f petition, a copy of the front of the envelope I sent it in, and a letter from the "SERVICE CENTER DIRECTOR" essentially stating that I didn't need to send the birth certificate and should wait until they ask for it if they decide it is necessary because it slows processing.