I'm surprised that this hasn't been posted yet. Has anyone heard anything through Chinese channels?
Generally speaking, the Chinese authorities are very hush and hush and at best rather vague about
recent counterintelligence operations.
For example, details concerning the
who was sentenced in 2015 and executed in 2016 for espionage was not
publicly disclosed until and after 《创新引领·国安砺剑》 was aired on CCTV
almost a decade later in 2024, in part due to recent and ongoing MSS efforts to encourage Chinese citizens to report suspicious activities.
Even with the release of an official documentary, the MSS and CCTV still elected to imply with visuals, rather than explicitly state who 黄宇 spied for.
As such, it's probably "going to be a while" at a minimum before the Chinese authorities disclose just where 刘某 worked or what he disclosed to hostile intelligence service(s).
However, odds are, either what 刘某 did was particularly damaging, or the Chinese authorities wanted to make an example of him to deter other would be traitors. Though both could be true. Otherwise he wouldn't have been executed.