Not sure why Redis is blamed for the "rug pull". They didn't relicense the old versions. They just said "sorry guys, we don't want to support this project under those terms anymore". They are under no obligation to do that, legal or moral. Don't like it? No problem, fork it and maintain it yourself (as many did). But don't demand of others to continue to support the project under those terms if they do not want to. This is FOSS working as intended.

All those people that contributed, did so to the FOSS version. Their contributions live on in all the forks, both FOSS and proprietary (by Amazon & co., and Redis before today). So not sure where "betrayal" supposedly happened. Maybe when Amazon used their contributions too?