@Tostiman The one that worked for me was "Hal's Neuro-Sama Mod". It was the only mod I had installed so I thought I would try to see if it fixed it and it did so I assumed all mods would but I guess not if none of yours worked. It still highlights like chrome or any other browser but it not bright and so barely noticeable. Although personally I don't like the theme in general so I am just gonna put up with the default for now and hope it changes.

The only solve I have found for this is to change the theme. All of opera's base themes have the same problem so you will need to get one from a mod. Hopefully they will add a way to change it in the future though