That is controlled from MediaWiki:Common.css. From what I can tell, it has always been that way; so I am not sure what the previous state is you want to revert to. Are you saying you don't want borders around the text?

The reverted version of that used to look like this but I have no idea how to revert it back? Do I just "undo" the code via Mediawiki

I see. That change was made by the other admin at the end of April. It is not simply a style change. They changed which feature they were using. Prior to the change, the page was using Tabview where as now it is using the CharacterTabs template (which is basically just links). Have you guys given any thought as to which feature is preferable? Because you can either change the styling of CharacterTabs to look like TabView or you can just switch back to Tabview.

This April 23, 2020 edit is where the change occurred. The version you like more is using TabView. The admin Glaciersong replaced TabView with Template:CharacterTabs.

I know you prefer how TabView looks, but I advise against using TabView for such purposes. So does FANDOM Staff, for that matter. FishTank--who is currently not acting as Staff--wrote a good article on Tab Use where he reviews issues with TabView; you might find it useful. The user who made that change is not 'just' a user, they're an admin; I assume they made the change due to this user's comment on their message wall, which advises against using TabView for the issues the Staff blog touches on.

Edit: I'm reminded of the case of a certain wiki whose new adopter in 2017 decided to supersede ParentTab on wikis with TabView, believing the latter to be an improvement. I recently revisited the wiki and discovered the same sysop this past December/January has been replacing TabView on articles with CharacterTabs... Good grief, all that work.

Edit x2: Sorry for all the edits; today is not my day.

Edit x3: Whoops, sorry, Andrewds; I started writing my comment before you replied! I take far too long when composing messages...

No worries. It happens fairly often; especially when a user is crafting a long reply.

It is true that TabView doesn't work on mobile. That said, while Character Tabs works, the appearance is very different between desktop and mobile. So either way, the mobile experience is going to no be as nice as the desktop experience.

That’s true and thank you all very much for letting me know about this. That being said, is there a way to change the color of the Character tabs instead of Pink, because it makes the color scheme look totally different. If you are able to show me the code you are more than welcome to.