It is worth bearing in mind that most of the contract manoueverings that NFL teams do (restructures in particular) don't actually reduce the dollar amount that counts against the cap, but pushes most of those dollars into future years. For example, the Mahomes restructure replaced around $48m of his base salary for this year with a bonus for the same amount - Mahomes still gets the same amount of money for 2025, but his salary cap figure goes down by around $38m (as the $48m is spread over 2025 to 2029 for cap purposes). The downside is that Mahomes now has cap numbers that are around $9.5m higher for each year from 2026 to 2029 - in other words, the cap space created now will need to be paid back later.
This is actually a relatively sensible thing to do most of the time, as the NFL salary cap has increased every year since it started back in the 1990s with one exception (2021, in response to the reduction in revenues in 2020 due to COVID). Those $9.5m payments in the Mahomes example above are likely to be a smaller percentage of the cap in future years - 3.4% of the $279.2m cap in 2025, but the cap is likely to be in the $350m-$400m range by 2029 (so the $9.5m is no more than 2.7% of the cap). A good analogy for this is using a credit card that has a negative interest rate, so the longer you wait, the less you have to pay.
The downside risk of doing this is that those deferred cap dollars only stay in the future as long as the player is under contract - if the player reaches the end of their contract, is traded or is released, all deferred cap dollars for future years are now counted against the current year's cap (1). This is why the salary cap position of the Saints improved by bringing back DE Chase Young - they would have around $9m of deferred signing bonus come onto their 2025 cap if he wasn't on the team...
(1) This can sometimes be spread over 2 years using what's called a 'post June 1st' trade or release.