the issue has been solved.
mine a different issue sorry
I contacted the Google Cloud Platform support and they indicated me that my payment method was suspended and needs verification. They provided me a form to fill and submit.
I had to upload the picture of my debit card.
I received a mail 10 mins later that my billing account is now verified. And then when I checked traccar again, it was working fine.
I enabled Reverse Geoencoding in Traccar following the official documentation. But when I click on show address, nothing happens. When I checked my Google Cloud platform API dashboard, I found this: API ERROR
Please help me resolve this.