Kate Middleton's mother, Carole Middleton, owns a party supplies company called Party Pieces.
The lack of children's birthday party supplies inspired the idea.
The business has been badly hit by the cost-of-living crisis in the UK.
According to a source, the company experienced a "terrible Christmas", which was made worse by postal strikes.
Mrs. Middleton has requested 90 days for Party Pieces to pay suppliers instead of 30.
The appeal to the suppliers did not go as Mrs Middleton had hoped.
Party Pieces Holdings had a net deficit of £1.35 million in 2021, with a loss of £285,506.
The company is still facing financial struggles due to the pandemic and other factors.
The Middleton family has not commented on the reports of Party Pieces' financial difficulties.