Stack Exchange is migrating to CommonMark and moving away from Markdown. Science Fiction & Fantasy has been scheduled for migration tomorrow, 2020-06-16. This is mainly an announcement of this change as there will be several things to look out for.
CommonMark is slightly different to Markdown
There are some subtle differences between the two, for example, most things now need a space after them i.e. quotes
> and headers
#. I encourage you to read the full post as it mentions a lot of these changes even if most (code) don't really apply here.
Not everything is being migrated
Currently only the posts that will look exactly the same upon changing to CommonMark will be migrated. This means some posts will be left in a limbo state of being rendered with Markdown but upon an edit will then be rendered with CommonMark (per my understanding). Please take extra care when editing old posts because of this.
There's a small chance for things to go wrong
So far 31 sites have been migrated and many problems fixed. However, there is still a small chance things could go wrong in the migration. If you spot any problems please report them on the main meta post linked above.
If you want to check for problems yourself, though there isn't much need, you can check your own posts that have been edited with the URL: https://scifi.stackexchange.com/users/current?tab=responses Here's a screenshot of what it looks like for me on Movies & TV.
You can also check all the migrations by looking at the Community user's All actions, revisions page where they are marked as the same above: Commonmark migration.
Note that in case of things going drastically wrong there is a built in rollback so everything will go back to how it was.