POST https://directline.botframework.com/v3/directline/conversations 403 (Forbidden)

I get this error since last week. Our bot worked fine and suddenly started giving us this error. Until last week we used https://directline.botframework.com/v3/directline/tokens/generate to generate a token. We then switched to https://europe.directline.botframework.com/v3/directline/tokens/generate because our resources (Azure Bot, Web App running the bot, WebApp running the web chat; all F0-tier) were created in West Europe last year but with no success.

The exact error is:

{
    "message": "ajax error 403",
    "xhr": {},
    "request": {
        "async": true,
        "crossDomain": false,
        "withCredentials": false,
        "headers": {
            "Accept": "application/json",
            "Content-Type": "application/json",
            "Authorization": "Bearer <Token>",
            "x-ms-bot-agent": "DirectLine/3.0 (directlinejs; WebChat/4.17.0 (Full) 0.15.5)",
            "X-Requested-With": "XMLHttpRequest"
        },
        "method": "POST",
        "responseType": "json",
        "timeout": 20000,
        "url": "https://directline.botframework.com/v3/directline/conversations",
        "body": "{\"user\":{}}"
    },
    "status": 403,
    "responseType": "json",
    "response": {
        "error": {
            "code": "RegionNotAllowed",
            "message": "The request received in france but target regional bot belongs to europe. Please check BaseURI  https://docs.microsoft.com/azure/bot-service/rest-api/bot-framework-rest-direct-line-3-0-api-reference?view=azure-bot-service-4.0#base-uri."
        }
    }
}

The error states that the request is received in france, but none of our resources were created in france. I already renewed the keys of the directline channel, which did not work.

Any help is appreciated.

Start with the Direct Line REST API base URI documentation referenced in the report, then compare the token-generation endpoint with the conversation POST endpoint and its RegionNotAllowed response. Reproduce the request using the listed URLs and confirm which regional endpoint is accepted; done means documenting a confirmed cause and resolution or identifying that the problem is outside this client library.