Two of my plants have a few spots like this on them. I removed all the areas I could see.

On my one plant it developed a spot like this that slowly spread but the branch was still alive and growing. Today I decided to remove that branch aswell and saw it was half dried out and half alive still. But the brown spot was a good 5 inches up the branch. That plant still has another branch I probably need to remove aswell. That one has been the most affected. I have tried to keep it further away from my other plants throughout the day. Now one of my other plants developed a few spots and I removed all of them I could see, mostly around the top of the plant.

I need to keep them going for another month at least, they seem otherwise healthy and growing fine.

Last year I bought just some run of the mill organic soil and had no problems. This year I bought the fancy fox farms stuff and it killed 3 of my seedlings and I've had a few of these fungal problems.