Just playing the devil's advocate here, but, I'd argue that it makes quite a lot of sense from a biological warfare perspective in terms of intelligence gathering on how different societies and countries behave against such a threat.
In particular, the pandemic has brought to the surface the how large schism between the two parties in the US, the constant politicization of science and nearly every other topic, the vast differences in perspective of different groups of the population, and provided information on the outcomes of different measures in different cultural landscapes, the level of preparation of different countries, the time it takes to figure out the correct response, and the responses of the people in guideline changes.
It has also shown that a well prepared, authoritarian country, with mRNA vaccines in the works can incur very minimal losses in terms of population due to swift vaccine rollout, hard lock-downs and strict measures.
China's losses compared to say UK, US, India, Russia and others have been very small if the data they have actually provided are to be believed.
But all of this is pure speculation from a random netizen so take it with huge grains of salt.
China figured it out and unleashed a global pandemic by opening the borders to not be a victim of day the CIA.
It’s possible it’s intentionally leaked but not by China
It would take some years until we properly see all the consequences, but I wouldn't be surprised if afterwards historians would note Covid-19 as a factor that benefited China in their long term competition w. "the west", not as a cost.
Like, 5k deaths is something that I wouldn't approve of for almost any reason, but looking back at documented 20th century history, planners (both in China and elsewhere) were clearly willing to pay such and even much higher costs for reasons of global politics/power play, so the mere existence of such a cost by itself certainly does not mean that it's implausible that someone would intentionally order a thing like that.