What does it mean if a submitted solution is marked in yellow instead of green in practice section?
It means it’s partially correct. If you open your submission, you’ll know how many sub-tasks have gone wrong/tle. This is present for only the problems where sub-tasks are defined and partial marks are allowed.
But it shows for Task #0 I gained 33% and for Task #1 I got 67% and for total it shows me a total of 100% score. Tasks is highlighted with green.
Can you link to the submission? You might be running into this problem.
Here’s the link: https://www.codechef.com/viewsolution/26894842
Is it a bug which is still not fixed?
It looks like that bug, yes.