I can confirm exactly what mfrank29 has stated as the same thing happened to me. Received iphone 12 pro for wife and 12 pro max for me. On upgrade from iphone 7 plus to 12 pro max did reset and immediately lost volume limit toggle. For iphone 7 plus upgrade on 12 pro did NOT reset and toggle still there. Both phones are now at 14.3 and pro (no reset) toggle still there, max, toggle still off. This is absolutely insane as now the only workaround is to constantly go and reset the health entries! What's worse is that my wife has SEVERE hearing loss (wears the strongest hearing aids available) and NEEDS to have volume very high to hear at all. Thankfully she has the pro with the toggle still available but I fear it will eventually go away too which will really suck. I have reported this to apple like I know many of you have done but got nothing from them at all. MANY people are hard of hearing and need to remove their hearing aids to listen to airpods or other buds and this limitation completely ignores them. Please apple, let US determine what is safe and not safe!