Webhook to teams gets error 400

I set up repository webooks to send to a teams channel
I am getting:

Headers
Alt-Svc: h3=":443",h3-29=":443"
Cache-Control: no-cache
Content-Length: 49
Content-Type: text/plain; charset=utf-8
Date: Thu, 31 Mar 2022 00:59:27 GMT
Expires: -1
Ms-Cv: k/z1jURdEQGLPfImCwE5NQ.1.1
Pragma: no-cache
Request-Id: 8df5fc93-5d44-0111-8b3d-f2260b013935
Server: Microsoft-IIS/10.0
Strict-Transport-Security: max-age=31536000; includeSubDomains; preload
X-Aspnet-Version: 4.0.30319
X-Backendhttpstatus: 400
X-Bepartition: CLNAMPRD19DSM03
X-Beserver: DM6PR19MB2410
X-Cafeserver: DS7PR03CA0352.NAMPRD03.PROD.OUTLOOK.COM
X-Calculatedbetarget: DM6PR19MB2410.NAMPRD19.PROD.OUTLOOK.COM
X-Calculatedfetarget: DS7PR03CU012.internal.outlook.com
X-Feproxyinfo: DS7PR03CA0352.NAMPRD03.PROD.OUTLOOK.COM
X-Feserver: DS7PR03CA0352
X-Firsthopcafeefz: MNZ
X-Powered-By: ASP.NET
X-Proxy-Backendserverstatus: 400
X-Proxy-Routingcorrectness: 1
X-Rum-Validated: 1
Body
Bad payload received by generic incoming webhook.```

I tried both application/json
and Headers

**Alt-Svc:** h3=":443",h3-29=":443" **Cache-Control:** no-cache **Content-Length:** 49 **Content-Type:** text/plain; charset=utf-8 **Date:** Thu, 31 Mar 2022 00:59:27 GMT **Expires:** -1 **Ms-Cv:** k/z1jURdEQGLPfImCwE5NQ.1.1 **Pragma:** no-cache **Request-Id:** 8df5fc93-5d44-0111-8b3d-f2260b013935 **Server:** Microsoft-IIS/10.0 **Strict-Transport-Security:** max-age=31536000; includeSubDomains; preload **X-Aspnet-Version:** 4.0.30319 **X-Backendhttpstatus:** 400 **X-Bepartition:** CLNAMPRD19DSM03 **X-Beserver:** DM6PR19MB2410 **X-Cafeserver:** DS7PR03CA0352.NAMPRD03.PROD.OUTLOOK.COM **X-Calculatedbetarget:** DM6PR19MB2410.NAMPRD19.PROD.OUTLOOK.COM **X-Calculatedfetarget:** DS7PR03CU012.internal.outlook.com **X-Feproxyinfo:** DS7PR03CA0352.NAMPRD03.PROD.OUTLOOK.COM **X-Feserver:** DS7PR03CA0352 **X-Firsthopcafeefz:** MNZ **X-Powered-By:** ASP.NET **X-Proxy-Backendserverstatus:** 400 **X-Proxy-Routingcorrectness:** 1 **X-Rum-Validated:** 1
Body
Bad payload received by generic incoming webhook.

Any idea what is wrong ?