ESA to UC Question please

I am a natural born worrier and today I am surprised to receive a letter from DWP regarding a new amount for ESA from 13/11/25.

I made an application for a managed migration from esa to Uc on the 9/10/25and have been using the journal in UC to answer required questions.

This letter says my new ESA amount from the migration date will be £152.29 pw which is approx half I receive currently.

I used the Citizens advice line to calculate my UC and their amount is £1369.53 pc month.

Interestingly, the amount of £152.29 was the amount before SDP was added to my esa claim following a back dated review. The new amount became £636.58 inc the SDP.

I wonder why if I am about to have a Uc claim why they would write to me about esa going forward and not include the SDP when nothing has changed.