I'm working with Trestle which is real estate MLS service to get property data etc. I have followed their WebApi docs but I'm getting this error whenever I hit their api it looks like their server thinks that request is from some BOT. Even they recommend using Postman to test api:
Its been 3 days and still cant find any fix. Any help?

You do not seem to be following this documentation correctly. https://docs-trestle.corelogic.com/GettingStarted/WebAPI
At the moment you are entering the token URL (https://api-prod.corelogic.com/trestle/oidc/connect/token) in the main Postman request URL field. The documentation states that you should use the Get New Access Token button on the Authorization tab of a request. You are entering the token URL in the main Postman request URL field.
This is a default flow for oAuth 2.0 requests in Postman. https://learning.postman.com/docs/postman/sending-api-requests/authorization/#oauth-20
Example: This could be your request to retrieve data:
https://api-prod.corelogic.com/trestle/odata/$metadataOn the Authorization tab you should select oAuth 2.0; select Get New Access Token and you will see a view which gives you the functionality you are looking for.
When successful, you will get a pop-up which you need to accept in order to use the API.