In the 1st step, maybe a year ago or so, they updated the Kasa app (v 3?) to only function with account and while being logged in at TP-Link servers to use your devices. And in now the 2nd step, they integrate Kasa into Tapo, which was always account-bound. The 3rd step is then probably the discontinuation of the Kasa app.
Kasa was their more premium product line, that was usable without internet connection and without manufacturer account - which is why I paid more to get those instead of the cheap Tapo products. But now my ‘smart’ power outlets are in a box in the basement collecting dust and I cannot recommend anyone to spend money on TP-Link smart products, as they remove features after sale.