@Lougle
I make your actual overpayment £159.90 (£24700-£21810= £2890. £2500 disregard. £2890-£2500=£390. Deduction is 41% £390×0.41= £159.90).
They may also be recovering "provisional overpayments" for the early part of 21/22.
Did your childcare costs go down because you were WFH, OP? If you were getting childcare included in your TCs and the costs fell, that would also account for part of the overpayment.
It may be worth ringing them and telling them that your income for this year will be less than last year, because you aren't doing all that overtime any more. They can do an in-year adjustment where hardship is involved, although they may take a bit of persuading.
I'd also check that they have applied the £2,500 disregard. Actually, ask them to explain their workings out, as it doesn't seem right to me (although I'm a bit out of practice at TCs these days, most of my clients are on UC nowadays). I used to be a dab hand at manually calculating TCs too!
If you're paying rent, make sure you tell HB your TCs have gone down, and your Housing Benefit should go up a bit, which will help.
If you're not paying rent, do an online check and see if you'd be better off on Universal Credit. You get more of your income disregarded on UC if you don't have housing costs, so people sometimes are. But bear in mind that the current figures for UC will include the £20pw "Covid uplift" and that will only be paid until the end of September. The monthly UC payment will fall by £86.66 a month after that.