This is the file I used for exiv2:
#
# To apply to a Pic do:
# $ exiv2 -m copyright.txt <file>
#
# This should blank personal id info
#
set Exif.Image.Model " "
set Exif.Image.Make " "
add Exif.Image.Copyright Ascii "Copyright (c) 2026 MYNAME MYEMAIL"
set Exif.Photo.UserComment "Can be shared using Creative Commons Attribution-ShareAlike 4.0 International Licence https://creativecommons.org/licenses/by-sa/4.0/"