The Hiveway source code is forked from Mastodon
(https://github.com/tootsuite/mastodon)
Hiveway currently has the following differences over Mastodon:
- Ethereum Blockchain integration
- UI was redesigned to be more friendly and with less items
- There is no Federated Timeline
- Mastodon branding replaced with Hiveway branding
Section 5:
a) The work must carry prominent notices stating that you modified it, and giving a relevant date.
And a (summary) reading of the license has no mention that retaining branding is required for "Conveying Modified Source Versions" and is probably a copyright violation if they did it.
The only thing I really see they did "wrong" is pulling commits without retaining the original committers ID and I'm not even sure that's even against the AGPL since that information would be lost if they distributed the sources as a tarball (which is perfectly fine).