@Alex Olivier (Cerbos) @Charith (Cerbos) is it recommended to deploy cerbos as service or sidecar?

Either method works well.

Both are supported and one isn't really recommended over the other - more just use the patterns that you are familiar with. Sidecar has the slight upper hand in my personal view as it will scale 1:1 with the particular container relying on it which is good for very variable workloads but this comes at the cost of more resources being used by all the containers rather than a shared service.