Does anyone know why tsubasa chronicle anime was canceled?
 

I loved that anime and was quite upset when they canceled it. I read the whole manga and it was really confusing. Does anyone know why it was canceled?

Anime wasn't canceled. 26 episode is one of standard anime formates. Long runners like Naruto, or One Piece are actualy more atypical.

^The OP is talking about why there's no third season.

The reason why there wasn't a third season is because CLAMP is very dissatisfied with how Bee Train adapted the manga, most especially the 2nd season which after the Library arc contains a lot of fillers.

Hence, they let Production I.G. continue the anime in the form of the OVAs (Tokyo Revelation, which adapted the Acid Tokyo arc and disregarded the fillers of Season 2, and Shuraiki which only adapted the Nihon arc).

I thought the anime was very boring and poorly executed, dropped it a few episodes into season 2. I haven't read the manga so no elitist comparison was required.

I don't think there's any proof of that going down. It was convenient speculation given the change in animation studio, but that's about it.

At any rate, the TV series was an NHK production, whereas the OVAs were commissioned separately by Kodansha. Most likely, I.G. secured the contracts for both since Bee Train was their subsidiary at the time of the NHK project (the two companies went their separate ways in 2006).