I spent some time in online chat with a senior advisor today. Currently using an iPhone SE Gen 2, upgraded to iOS 14.0.1 from iOS 13.7 last week and have experienced issues with intermittent disconnects from Wifi since then. The issue occurred every few minutes, would result in my device disconnecting from the Wifi and connecting via LTE or 4G (whichever was available). After trying the basic troubleshooting (Wifi manual disconnect, device restarts, network reset) I was advised to delete any VPN configurations I had within General > Settings > VPN. From there, I restarted my device and have not experienced issues since.