ChatGPT does a similar thing
My personal ChatGPT account is a Business account with 2 seats at $30/ea (minimum 2 seats required).
Why? Because for $60 you get ChatGPT Pro, significantly cheaper than the $100 normally required for the next level personal plan!
Is that some sort of legacy pricing? because on https://chatgpt.com/pricing/?type=team I see an option of either £15/ month or £75/ month, per seat, 2 seats required. So it's more expensive than a single £89/ month pro subscription.