Support for FCALL_RO command was added in version 9.0.3 with the name FCallRo().
https://pkg.go.dev/github.com/redis/go-redis/v9@v9.0.3#Client.FCallRo

However, other read-only commands are named with ~RO() convention. (e.g. EvalRO(), EvalShaRO(), SortRO())
https://pkg.go.dev/github.com/redis/go-redis/v9@v9.0.3#Client.EvalRO
https://pkg.go.dev/github.com/redis/go-redis/v9@v9.0.3#Client.EvalShaRO
https://pkg.go.dev/github.com/redis/go-redis/v9@v9.0.3#Client.SortRO

The slight naming inconsistency here could be surprising to users, especially for people migrating their code from using EVAL(SHA)_RO to FCALL_RO.

One possible solution could be adding FCallRO() and deprecating FCallRo().