Invalid access token

Given that the access token no longer works even in the environment where it originally worked, it sounds like the access token was likely revoked.

• the user or team admin can revoke all access tokens for an app by unlinking it on any of the following Dropbox web pages:
• the Connected apps page
• the Security checkup page
• the Team apps page on the Settings section of Business Admin console
• the team member’s page on the Members section of the Business Admin console
• any client with the access token can revoke the access token by calling /2/auth/token/revoke
• the GitHub-Dropbox token scanning partnership can revoke access tokens found publicly posted on GitHub
• if the app uses the "app folder" access type, the access token can effectively be disabled by deleting the app folder itself in the Dropbox account, via the Dropbox website or any client
• the app can be disabled
• the account that owns the app can be disabled
• the connected account/team can be disabled