You may convey verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice; keep intact all notices stating that this License and any non-permissive terms added in accord with section 7 apply to the code; keep intact all notices of the absence of any warranty; and give all recipients a copy of this License along with the Program.
What it says is, they are free to make copies and transmit those copies, so long as the copyright notice is preserved. If you have a copyright.txt in your repos, they have to keep that. That's separate from the license; the AGPL is not the copyright notice, only a license to redistribute. It's part of the whole of the copyright, but not all of it. Attribution is explicitly required.That said, if you had no copyright notice, that is a copyright notice - the license allows them to distribute that lack of notice. Add a copyright.txt to your repos, and if they update their copies to strip it, you've got right to send a takedown.
[0]It's a whole lot of other bad things though: bad practice, and confusing, and something I'd never considered doing.