@Naps and nuts 💀 hello, it's absolutely fine but luckily it is not too late to add in a spoiler tag. All you have to do is edit your comment. The way to to do this is go to your profile and there you will find notification, reading history, my list, etc. Go to my comment, find the comment you are looking to edit, and click the three dots beside it.
Spoiler!
Once you have edited your comment a small notice in red (Edited) will be printed at the bottom of the comment indicating to others that the comment is edited and may not be the original.
Hope this helps.
Hope this helps.