GPL begins with following:
> GNU GENERAL PUBLIC LICENSE
> Version 3, 29 June 2007
> Copyright © 2007 Free Software Foundation, Inc. <https://fsf.org/>
> Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.
This is one reason I think SSPL is bit problematic as afaik it's just AGPL with changes, something that is explicitly forbidden.