I am word for word reposting @Evanbear1 's post as this is an identical issue that came up last week and was solved solved here:
If you try adding indenting and/or spacing to your game description regardless of the text it will unformat the entire description and put it as one long string of text. From my experience this is happening for every single account and every single game. If you update your Roblox game description at all it will change it to this.
Hey everyone, our teams have published an update to fix this bug! Please check if the issue is resolved for you and let us know if you have any questions