Does credit report tank after marriage?

Hello all!

Long time lurker but first time poster.

I got married back in October, wife changed her name to mine across everything we could possibly think of, happy days.

However we recently noticed her credit report has dropped a fair amount and the only real change I can see is that it now says she has been on the electoral roll for 4 months, which is definitely not true.

Does getting married affect everyone in this way or is it abnormal? Have I forgotten to tell a department?

We are looking to buy a new house in around a year so would like to try get this fixed by then.

I will massively appreciate any advice offered, thank you!