Query runtime is slow in view

I am in need of your expert suggestions for a weird situation and any pointers are appreciated.

The situation is - There’s a view containing a UNION query, which I tuned and results are coming in less than a second when running in SQL developer. But, when I replaced the existing view query with the tuned query and select it from the view then it started taking more than 2 minutes.

I have never seen such a situation before when the query is running within a second but when used inside view starts taking the time.