Thanks for your suggestion. but I'm undone.
at first, while setting up the monetization, I have deactivated the ad tester on mobile for that domain. switched on for desktop and tablet only.
After one month I have activated ad tester for mobile devices. but the ads not showing on mobile. I have done everything as video tutorials and articles related to monetization. but did not work.
I'm unable to contact the support team or create a ticket.
if I create a ticket, it automatically closes.