A mast covering is one component of RCS reduction design. And Iran has indicated there will be 7 Mowj ships. 3 have been built, 1 is being repaired (Damavand), and 3 more are in construction phases. I think after the 7th is done they will move on from the design.
View attachment 833465
The Zumwalt for example has a an RCS of a fishing boat using the latest (at the time of prototype stage) in Low observable RCS design construction. Unfortunately like many US designs it’s other costs caused the ship price to balloon to very high levels. Not mass producing caused price per ship to remain very high when RD & production costs were accounted for.