What's the concept of the security council? Russia loses a war to Ukraine so it loses it's seat? Does it go to Ukraine? Or maybe it should go to Afghanistan because of the failed Soviet invasion.
The seat doesn't belong to Afghanistan nor to Russia, but to the USSR. Ukraine was as much a member state of the USSR as Russia. If the UN decides that Ukraine is a more legitimate representative of the USSR than Russia is, it can decide to let Ukraine fill the seat.
The seat obviously does belong to the Russian federation, as they have been sending representatives for thirty years and the other members have always recognized that representative.
That's the thing: it does not. It literally, explicitly belongs to the USSR. Russia has been allowed to fill the seat by agreement. The article points out that that agreement could change, and gives an example where that has happened before.
Well, Taiwan also had a permanent seat at the UN Security Council, had been sending its representatives for more than 20 years, and other members had no objections. But one day that seat was taken away from them and given to China.
There was always objections since inception. ROC tried to exclude PRC from any UN representation (how turntables have turned), USSR protested exclusion of PRC in the 50s, host of "third world" PRC friendly nations petitioned for ROC to be replaced by PRC in the 60s. Was succession in 71 (76 for, 35 against, 17 abstain). Seeing how global south is indifferent about RU's invasion of UKR, doubtful there's going to be coordination to form plurarily bloc to vote RU out even if that's technically possible.