Doesn't mean we have £400m to spend, it means we could spend up to £400m and still be FFP compliant based on how much profit the club have made and our very modest wages to turnover ratio.
That report calculated what we could spend over a 10 year period, the firsrt 7-8 years of the decade the spending was largely minimal, the other 2-3 years the average spend per year has shot up hence why since 2019 we have the 7th highest net spend in the league.
So when you say they haven't spent, well initially yes but they have spent recently but spent poorly.