What the system tracked
FIFA's explanation of the Qatar 2022 system describes 12 tracking cameras under the stadium roof and up to 29 data points per player, sampled 50 times per second. These tracked the body positions relevant to offside. A sensor in the match ball supplied data to help identify when the ball was played.
The software could combine the information and send an alert about a potential offside to the video officials. They still had to validate the proposed kick point and offside line before communicating with the referee. This human check is the reason for the term semi-automated.
Source [1]What the animation shows
After the officials' decision, the same positional data could produce a 3D animation for spectators. That graphic explains the relevant body positions; it is a visualization of tracked data rather than an ordinary television camera angle.
The technology supports a specific part of refereeing. It should not be described as automatically deciding every foul, handball or disputed incident. Argentina's match against Saudi Arabia, where several first-half efforts were disallowed for offside, provides useful tournament context. A disallowed effort is excluded from the official score even when the attacking move ended with the ball in the net.
Source [1]