Apple in releasing 12.4 made a mistake. They released with software the ability to jail break the system. Jail breaking the system goes way back to introduce new functionality that is not supported by Apple.
The problem with a jail broken phone is that you could end up with Malware. Something such as this is not worth taking the risk just for some unsupported piece of functionality.
Apple Acted Fast
Fortunately Apple was on top of this fast. 12.4.1 has already been pushed out. It is very wise for all to do this upgrade as soon as possible.