Ostensibly, China's main goal with continued lockdowns after widespread vaccination, and unlike all the misinformation, China has one of the highest basic vaccination rates in the world and their vaccines are indeed effective at lowering deaths, would be either waiting out other effective treatments to lower the death rates even more or waiting out for long Covid symptoms to manifest and hopefully be solved in the rest of the world to spare their people from long-term disability.

More and more those goals seem far away, long Covid isn't being taken seriously anywhere and it be could multiple years if not even longer for that to be resolved better and new treatments also seem to be along the same lines, they just aren't coming like we would hope. The good news for China at least is that they have multiple years lagging behind if long Covid does build up enough in a population to massively cripple an economy, meaning that they will (hopefully) be able to implement policies that would address this and apply the brakes before their own economy falls to shambles.

So anyway China is stuck with two options. Open up for the frustrated population, who like every other human society on the world isn't really looking at this rationally enough and are getting increasingly more pissed at the lockdowns especially as you struggle with supplies more and more, or keep them locked down and noncompliance becomes more and more common and the economy just keeps suffering.

Now to be clear, I see no reason for why China would undergo the "ok then, just let it rip option" but it might be what they thought the population was wanting, or perhaps some of the lockdown opposing officials finally got their input. I really do not know.