Correct, it’s not completely empty, but I went from 500+ to 300ish. I’m going around now refollowing people I know I didn’t unfollow. 

I believe the loss of 200ish follows predates my use of the Fountain update. But I’m less sure that’s true of my apparent “refollowing” of people I’d unfollowed. 
I’ve been seeing notes from unfollowed people for the longest time of all these bugs, but it at least hadn’t been claiming anywhere that I was still following them. 

It’s entirely likely it wasn’t Fountain’s fault, I just don’t know what happened, and I think it is the only new client I’ve used. 

The timeline here is so uncertain, sorry! 

 Ok interesting. I did some investigation and it looks like your latest follow list was only on certain relays. Other relays had various copies of old follow lists. Fountain does try to find the latest follow list but it's possible that it didn't. I have updated the logic for searching for the latest follow list for the next version which should catch cases like this. I'm still not sure it was Fountain that did this - but either way the additional checks will be helpful.