It’s confusing the taz asked the responsible authorities. The important part is the update at the end:

An earlier version stated that the BMI [Federal Ministry for Interior] and the Berlin police had confirmed the ban to the taz. The police had initially referred the taz to the BMI, the BMI to the Berlin Senate Department of the Interior. However, neither had initially denied that Varoufakis had been banned. A spokeswoman for the Berlin Interior Administration responded to a corresponding query on Saturday evening, stating that a ban on Mr. Varoufakis had not been issued by the LEA (State Office for Immigration) as a subordinate authority of the Senate Department for Interior and Sport. (Translated with deepl.)

Nothing outrageous about banning a liar and propagandist from spreading lies and propaganda in our country.

Ffs... he even published the speech he was going to give there and it was hard to swallow so much bullshit. On the plus side, he basically answered questions about Hamas atrocities and their threat to Israel with (paraphrasing) "I condemn atrocities in general but here I celebrate the people that attacked Israel" and "What threat? Israel is only afraid because of rampant anti-semitism in Europe and America".

So we know were he stands and if you ask me he can go get fucked with the Hamas buddies he supports.