Receipt of lump sum pension effect o new style esa

My partner has been receiving new style contributary based ESA for about 2 years. Just before the end of 2021 tax year he cashed in a small pension and got a lump sum of around £5467 paid into his bank account on 6th April 2021. He didnt think about telling the DWP about this at the time but I am worried that it would count as a change of circumstances and his benefit could be stopped if we tell them now. I think you are allowed one off lump sums and they dont affect this type of ESA but concerned about informing them now as 2 months later. Advice about best way to proceed would be welcome.

Many thanks for your reply Gary. Do you think we need to tell the DWP about the lump sum even though it will be ignored. Im thinking yes to avoid any potential problems but assume HMRC will tell them as they have deducted tax which he is owed. I'm a bit worried about his ESAbeing stopped if they find out we havent told them even though the lump sum is allowed.

Thanks Gary, I'll do that. It seems impossible to get through on the phone so will write to them.