Hi @Shreyas Dravekar ,
We apologize for the frustration that this issue may have caused.
Currently v2.6.2 is not available in Microsoft-hosted agents but it is required in your Azure app service. Try deploying self-hosted Linux agent and install ruby v2.6.2 on your local machine. so using this private agent in pipeline will use ruby v2.6.2.
Hope that helps. Please let us know if you further questions.
-Grace