Pinpoint Transactional SMS marked as SPAM in UK

We are using a set of custom lambdas to implement OTP login to a Cognito instance. To send the text messages with the password (eg, sms), we are using the pinpoint api with a configured 10DLC campaign/phone number. We also have another phone number (and relevant campaign) setup for promotional messages.

Since 13:30 today (30/05/2022), we cannot send the OTP messages to UK based phone number (most of our devs are UK based). The messages work as expected for US, RO and (!!!)PK number (we are deploying code atm to block PK). The SMS sent to UK numbers are logged as SPAM, see example:

{"event_type": "_SMS.FAILURE", "event_timestamp": 1653917224341, "arrival_timestamp": 1653917224468, "event_version": "3.1", "attributes": {"sender_request_id": "...", "origination_phone_number": "...", "destination_phone_number": "+44myphonenumber", "record_status": "SPAM", "iso_country_code": "GB", "number_of_message_parts": "1", "message_id": "...", "message_type": "Transactional"}, "metrics": {"price_in_millicents_usd": 3888}}

This is incredible frustrating since none of my devs can log in to the app (we are developing).