Unable to deliver e-mail from Office 365

I am using Office 365 as my e-mail hosting provider.

Last week I signed up for a free trial and added my hostname.
Pointed my NS records to Cloudflare and all of a sudden I had massive e-mail issues.

All e-mail from other O365 environment would not arrive anymore. Other providers like private or google (gmail) works fine, but only O365 would not arrive.

My company email is also in O365 and i would send test mails from that environment.
Below are the error bounce messages.

5/20/2022 11:11:27 AM - Server at DB9PR02MB6538.eurprd02.prod.outlook.com returned ‘550 5.4.312 Message expired, DNS query failed(ServerFailure)’
5/20/2022 11:01:15 AM - Server at xxxx ( returned ‘450 4.4.312 DNS query failed [Message=ServerFailure] [LastAttemptedServerName=xxxx] VE1EUR01FT101.eop-EUR01.prod.protection.outlook.com

Anybody also has issues when running the Cloudflare nameservers in combination with O365?

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