Hi @DS-LIT,
Welcome to the Auth0 Community!
I performed a quick test with the access token you tried to verify in your screenshot and found that the error is happening because the payload is not a valid JSON object.
Because of that, could you please share with me the exact code and steps you took to get an access token?
For your reference, you might find our Get Access Tokens documentation helpful.
I look forward to your reply.
Thanks,
Rueben