We have recently started using ValKey, having previously used Redis, as the cloud hosting service we use stopped supporting Redis in the last couple of weeks; we started testing a few weeks before that, then migrated across to ValKey in a couple of ChirpStack instances.
Dragonfly was another option open to us, but we don’t need the top end performance that it potentially provides, the licence associated with ValKey gave us more confidence that we would not end up in the same situation as Redis, and from reading other ChirpStack blog posts (e.g. Support of Valkey after Redis License change - #3 by rekcaiot) it seemed like the preferred future solution if compatibility migrates away from Redis.
So far we have not noticed any issues, either when using the ChirpStack user interface or in our customer integration that subscribes to the streams that ChirpStack publishes frames and device events. The cloud hosting service provides the clustered version of ValKey.