Flipkart — Not providing GST invoice for Moto g31 smartphone

Motorola phones are sold in flipkart as mentioned by their own site i.e https://www.motorola.in/motorola-all-home.

But flipkart is not giving GST invoice for moto phone e.g moto g31 smart phone .

After enquiring and asking for for the GST invoice, flipkart is giving reason why they are not prociding GST invoice as they are adding some free offers to customers which customer never want to add .

How flipkart is allowed to sell any product without GST invoice ?
How any seller is allowed to sell products without GST invoice ?
Seller details in flipkart is : TREASURE HAUL ONLINE