> This is not true of the AGPL, which has additional redistribution requirements meant to prevent (what copyleft activists perceive as) this kind of abuse.
It's important to note that the "kind of abuse" AGPL is fighting is denying the end user the four freedoms. Eg freedom zero: if Amazon shuts down aurora, you lose the right to run the program.
Upstreaming of modifications is kind of orthogonal to the GPL licenses - sure if A sells a program to B under the gpl, B modifies it and sells it to C, C will have the [ed: new and modified] source and may give it to anyone - including back to A.
But the main thing gpl tries to enforce is that C will be able to use and improve the program as needed.
The AGPL is a reaction to the rise of rent-a-program (SaaS etc) - where the user has very few of the four freedoms guaranteed - both if the provider goes bankrupt, and if the provider makes changes.