Ghost Likes
One does not simply unlike old tweets.
Did you just try deleting all of your likes with Cyd but notice that some of your likes are still showing up on X? X (and Twitter before it) works in mysterious ways. For reasons unknown, old likes may still appear in your like history, but they can't be unliked. Cyd refers to these as ghost likes.
When you like a tweet on X, the heart icon turns red. When you unlike it, it turns grey again. If there are tweets listed in your likes but the heart icon is grey instead of red – meaning you can't unlike it – then this is a ghost like.
The only way to delete a ghost like is to like it again, and then it lets you unlike it. This is very noisy because every time you re-like an old tweet, the user will get a notification.
If you have many ghost likes, Cyd recommends you just don't worry about deleting them. Likes on X are private, so your ghost like history is not accessible to the public.