Never heard of Medivia before, but looking at screenshots and their site, that is absolutely some sort of fork/copy of Tibia. Even the world map is basically same shape, with locations shifted slightly and renamed, and the game interface is the same. I think they may even be using the old sprites from before a UI revamp a bit over a decade ago, from when I played Tibia.

Edit: Found this [0] which states Medivia originally started as a private Tibia server that eventually evolved into its own game. People were only just starting to make private Tibia servers when I left (or maybe they were only just starting to become popular, not sure anymore), which explains why I hadn't heard of this.

Tibia was created in 1997, I played roughly 2002 - 2006. Looks like Medivia was first created in 2009 [1], I would guess probably still just a private server at the time.

[0] https://www.reddit.com/r/MMORPG/comments/i480jd/medivia_4_ol...

[1] https://www.reddit.com/r/MediviaMMO/ (right sidebar)

Since they mentioned the late 90s, I think it's more likely they meant Medievia[1], which has been online since 1992.

[1]: http://www.medievia.com/