Bluetooth + Wi-Fi Explanation Please

So about 4 or 5 Apple Software Updates ago I lost the stability of my Bluetooth and Wi-Fi on my iPhone 5S. What was happening was with Bluetooth I would get it to load but it would drop after about 2 mins, sometimes when I turned it on using the white button instead of the button showing green I just saw a spinning circle, BT would not load. The very same thing occurred with Wi-Fi, it might connect then drop and the wi-fi would then not load at all. Anyway over that period of time which was considerable I tried all the reported fixes, re-setting networks, doing it manually, there was nothing I did not try without success, I relied on Mobile Data. This convinced me that BT and Wi-Fi were on the same board or logic circut and it got cracked or something when the phone was dropped. However I recently(2 months ago v.1) got a pressie of Apples AirPods and it was annoying that I could not use them with my iPhone.

Last month I started looking at getting an upgrade, an iPhone XR maybe and then Apple Software Update 12.4 was released. I had not been watching for an update but Automatic Updating was enabled so I updated the phone. Lo and behold Bluetooth and Wi-Fi is back working perfectly after the bones of 2 years being faulty. While I am happy to have a working phone I am perplexed as to how this happened. Would anyone have any idea how something like this could occur. When it happened first it was straight after a software update, I actually came on this site blaming the update for wrecking my phone, of course I got nowhere with that. Over time and more updates I got less convinced but I am now pretty sure it was an update that broke it and an update that fixed it. Any ideas appreciated or indeed if anyone else has expirenced this, I am pretty sure Apple will not admit it even if they do know.