Why am I recieving random notifications labelled "new topic"?

I open the site, and in the right top corner next to the big letter C which is my avatar, there is a little dot.
“Great!!”, me thinks to myself—somebody has responded to one of my posts, or somebody has quoted me. So I guess somebody has appreciated yet another one of my great gems of wisdom! I wonder which gem it is?
So , all excitedly, I click on my avatar, thinking I’ll be pointed back to whichever thread is mentioned there, and continue sharing my wonderful wisdom with those who surely are waiting impatiently to hear from me.

But no,no no. Life ain’t so sweet.
That little dot next to my name means nothing.
Nobody responded to me.
Nobody quoted me.
Nobody loves me.
Poor me, I am heartbroken.

The little dot just means that there’s a notification telling me that some random thread has been created as a “new topic”.
Why does Discord suddenly think I care about that new thread? Why does the bot notify me privately about it?
And why did this just start happening a few days ago?

It’s irritating, like spam.
How do I block it, but still continue receiving the notifications which are relevant to the threads I’ve posted in?

The only preference I can find related to “new topics” is in Preferences > Tags.

I’d link it, but, for some reason Discourse makes all preferences relative to your account. So I guess yours would be

https://boards.straightdope.com/u/chappachula/preferences/tags