iPhone 14 Pro Max not automatically switching from 5G to 4G when 5G performance drops

I have found that the threshold at which the iPhone 14 automatically switches from 5G to 4G, when the 5G signal performance reduces, is much lower than that of the iPhone 12 and 13.

My iPhone 14 works perfect in a strong 5G signal area on 5G; likewise in a strong 4G area (with no 5G), it works perfectly on 4G.

The problem occurs in an area where the 5G signal is not strong and at times drops to a 1-bar signal (occasional 2-bar).

Apple's online chat did not have an answer and referred me to the iPhone User Guide: View or change cellular data settings on iPhone "Enable Smart Data mode to optimize battery life:Tap Voice & Data, then choose 5G Auto. In this mode, your iPhone automatically switches to LTE when 5G speeds don’t provide noticeably better performance."

This automatic switching worked perfectly on my iPhone 12 and 13.  On both these phones, when the 5G signal performance dropped (usually to 1-bar but occasionally 2) both would automatically switch to 4G.

This does not happen on my iPhone 14.  In exactly the same less than optimal 5G area, with exactly the same settings, when the 5G signal drops to 1-bar (occasionally 2) instead of automatically switching to 4G [almost stubbornly] the iPhone 14 remains on 5G.  The result, all data transmission stop.  For example: Safari has no internet connection; mobile apps (say a banking app) no longer connect; a mobile app like a radio station stops playing; etc.  If I now manually switch my iPhone 14 to 4G, all data transmission resumes.

And of course, my iPhone 14 is on the latest iOS, 16.4.1 (although, this was also an issue on all previous iOS on my iPhone 14); I have updated/restarted my network settings; I have tried all available settings (Voice & data: 5G Auto; 5G On; 4G | Data Mode: Allow More Data on 5G; Standard; Low Data Mode); I have forced restarted my iPhone at every setting/update; I have tested on 100% and less that 20% battery and when connected to power - all to no avail.

What I have not tested is a UK Vodafone physical Sim in a less than optimal 5G area - simply because I do not have one: I use an eSim.  But them, I used an eSim with my iPhone 12 and 13 and did not experience this issue.  So, I don't believe the eSim is an issue.  I have also not experienced a less than optimal 5G signal in Thailand using both an eSim and physical Sim.  All areas I have visited there has had a full, strong, 5G signal - so I've never experienced this issue there.  Indeed, I have seen mobile data speeds there of 1Gbps - surreal!

Additionally, I am aware that I am not the only iPhone 14 user experiencing this behaviour/issue.  In trying to resolve this issue, I have spoken to 2 others who, having upgraded from an iPhone 12 and 13 respectively, are experiencing the exact same issue with their iPhone 14 in comparison to their iPhone 12/13.

So, in conclusion, I do not believe that my iPhone 14's failure to switch automatically from 5G to 4G, when the 5G "speeds don’t provide noticeably better performance", is anything to do with my iPhone itself, my iPhone settings, using an eSim or physical Sim, or the Vodafone mobile network.

My conclusion is that the threshold at which the iPhone 14 automatically switches from 5G to 4G, when the 5G performance drops, is much lower than the threshold for the iPhone 12/13's automatic switching from 5G to 4G.  As a result, the iPhone 14 latches onto/remains connected to a 5G signal even when the performance of that 5G signal is incapable of supporting mobile data.

I welcome any comments/advice.