I don't know what client is doing it, but I've been seeing a lot of double hashtags/pound symbols before the words over the past couple days.
Discussion
It might be Primal? 
Here's a nos.social account with the double hashtags.
I'm not sure what this is all about… but I am only seeing one hashtag on my end? I posted this photo via nostr build - maybe that has something to do with it? I use Primal or Nos depending on my mood
It's nothing you've done, but something a client is doing. 
Do you remember which client you used to post this note?
This is why I was asking, I've been busy last week, and when I came back I started to see all this notes with double hashtags.
Represents an increase in the hash rate required for notes on Nostr 😏
> I don't know what client is doing it
Amethyst renders markdown.