Why I didn't get any revenue from top countries installed app?

Unity Services
1

I’m using Unity ads on my android application.
The most users on my application come from Indian, but I didn’t receive any revenue from this country.

But I only received some revenue from some countries like Thailand, or other countries which have fewer users installed the application.

Help me to check this situation. Thank you in advance!!!

2

I tried Unity Ads for a week or a little more. Almost no revenue. I switched to Admob & in little over 3 days I got about 5$. Weird since Unity should be trying to compete with google & offer even better reward for install/completed video since I only use reward videos!