That only applies to redistributors, not to the original author. The way the GPL works, is that the author absconds some of the copyright they hold by default, in exchange for people taking advantage of that committing to publishing even modified source code whenever they redistribute it.
Abscond means to hide or steal away. I think you mean abdicate? That would make more sense in this context. It's still not quite right though, the author of a GPL work fully retains the copyright of their work, and merely give a license to others.
Oh sorry yes, I'm not a native speaker, thanks. And yes, they commit to not exercising some of the rights they have been granted as part of the copyright they do indeed still hold.
https://www.gnu.org/licenses/gpl-faq.html#MustSourceBuildToM...
and
https://www.gnu.org/licenses/gpl-3.0.txt section 6, point d