e.g. I want to find out if any problem is asked in any contest from practice area. How can I do that?
AFAIK this is not possible.
Maybe I didn’t understand you well. You want for each problem in practice find the contest the problem is from? That’s not possible.
But to find it for some newer problem it’s possible. For example Bogosort (actually 6th in problem list in practice (easy)), when you click on the problem, there is Editorial link (in the part after problem statement) and from editorial you can get to contest (there are problem links). Those editorial links are not available for all problems.