At first I thought this is BS, like, TB3 landed around 2 months ago? And they were collecting tasks for 4.5+ months!
Note that there are NO new tasks in TB4: some got removed, some were modified. Which means some of the tasks are 5+ months old and were published alongside solutions/graders openly.
Not saying Zai trained on them, but I'm not buying that none of the companies have used well-prepared envs available for free on GitHub in a very accessible form (Harbour-compatible).