Unexpected ESA letter that I dont understand

I received a letter with the title YOUR CLAIM FOR EMPLOYMENT AND SUPPORT ALLOWANCE. A CHANGE IN THE EMPLOYMENT AND SUPPORT ALLOWANCE RATE PAYABLE. It says that from 7 Apr 2023 my new rate will be £135.35 ( which it is at the moment). This is because of a change in money coming in (Im not aware of any change), and that it's based on 2008/9 tax year. Been trying for the past hour and a bit to get through. Does anyone know what this letter could possbily mean at all? What is the change in money as my circumstances havent changed? Why does it change next year (is that not quite far away)? And why use the tax year of 14 years ago?

Hi mumsgirl

Usually you get a letter when benefit rates change at the begining of April.

The only way you will get an answer is to contact ESA enquiry line; 0800 169 0310.

The best time to try and contact them is first thing in the morning 9.00 am.

Let us know how you get on.

Gary