They sent me this link, my plates are LEGAL
In particular this stands out;
On or after 28 September 2021
You will need to display a UK sticker clearly on the rear of your vehicle if your number plate has any of the following:
- a GB identifier with the Union flag (also known as the Union Jack)
- a Euro symbol
- a national flag of England, Scotland or Wales
- numbers and letters only - no flag or identifier
If your number plate includes the UK identifier with the Union flag (also known as the Union Jack), you do not need a UK sticker.
If you’re in Spain, Cyprus or Malta, you must display a UK sticker no matter what is on your number plate.
If you have a GB sticker, cover or remove it.
View attachment 129986View attachment 129987
How to display number or licence plates, get plates made up, replace lost, damaged or stolen plates, and the national letters, flags and symbols you can display.
www.gov.uk