Below is an article by the BBC:

Pictures from the 30 April UEFA Champions League semi-final between Atletico and Chelsea appeared the next day in the Jam-e Jam newspaper, but without the sponsor's logo on the players' shirts. The move was spotted by a popular Azerbaijani Facebook group, which posted a photo of the newspaper page along with the caption: "Iran could not stand the word Azerbaijan."

Atletico Madrid is frank about the political dimension of its sponsorship deal with Azerbaijan, saying the intention is to "promote the image of Azerbaijan" and help raise the country's profile with international audiences. "The name of Azerbaijan will reach all over the world," the club says on its website.

Relations between Iran and Azerbaijan have sometimes been tense. Azerbaijan has at times accused Tehran of supporting Armenia, and Iran has criticised Baku over its ties with the West. Iran also has a large ethnic Azerbaijani population but the authorities are wary of allowing a strong community identity to develop.

Such sensitivities did not stop other Iranian news outlets from publishing unedited photos of the same match. Even the Jam-e Jam website carries an image in which the Azerbaijan sponsorship slogan can be seen.

It is not clear if the Jam-e Jam newspaper's action was taken for political reasons. Some Iranian newspapers routinely edit out photos of commercial logos.