Probably9857 If 5G offered any significant security improvements (or known additional risks), that would likely have been discussed extensively here, and a 5G-only feature would have been added much sooner.
Yes, the cellular network isn't secure and 4G / 5G Only is simply a way of reducing the attack surface, but that's also because before, 5G coverage was much less deployed than 4G coverage, 5G coverage is now expanding.