I’d only recommend Pi 4+ for HA:
https://community.monzo.com/t/octopus-energy-chat/148190/118?u=davidwalton
I also had a number of fundamental issues running HA with a Pi 3, which has now been repurposed as a reliable Plex server. Never had an issue with HA on the Pi 4
And start from scratch when changing hardware platforms - there can be all sorts of random variables introduced when trying to port data from one hardware platform to another. Good luck 