@Ramen Thank you so much for your detailed instructions. I changed the node version to 14.18.0 and it worked on 4.3. Btw, I was using v16.18.1.
Another interesting way I was able to solve the issue was by downloading the master branch of monster-ui, and monster-voip and being successful in building from scratch. Once the building was completed, I replaced the entire monster-ui folder with the latest files and folder from the dist folder and that seems to have worked. It was kinda long path but totally worth it!!