Congratulations
.
As the letter said: Don't worry, you don't need to do anything.
They are getting rid of BRP cards completely on 31st December 2024 and moving everything online... so for the last few years, for all visas valid past the end of 2024, every BRP card has been issued with an expiry date of 31st December 2024, regardless of the actual length of the visa.
From 1st January 2025, you will instead be able to verify your immigration status online instead of with a BRP card.
See here for more information:
https://www.gov.uk/biometric-residence-permits/report-problemFrom that page:
If your BRP expires on 31 December 2024
You do not need to tell UKVI if your BRP expires on 31 December 2024 but your immigration status (for example, your visa) allows you to stay longer.
You will not need a BRP from 1 January 2025. You’ll be able to prove your immigration status online, without a BRP.
UKVI will update their information on how to prove your immigration status in early 2024. You do not need to do anything and your immigration status will not be affected.
I'm surprised they don't explicitly explain this in the approval letter, as several people who received their ILR recently have been worried about the same thing.