The Wall Street Journal has the report:

Chinese representatives conceded in a clandestine December gathering that Beijing was responsible for a widespread array of concerning cyberattacks targeting U.S. infrastructure, as per sources acquainted with the situation, highlighting the escalating tensions between the two global powers.

The Chinese team connected years of infiltration into computer systems at U.S. ports, water facilities, airports, and other locations, to the growing support of U.S. policies favoring Taiwan, according to sources who wished to remain anonymous.

The acknowledgment wasn’t overt:

The comments made by the Chinese official during the December gathering were indirect and somewhat unclear, yet most members of the American delegation present interpreted it as a covert acknowledgment and a caution to the U.S. regarding Taiwan, stated a former U.S. official familiar with the discussions.

No shocker.