The Epic Boon of Spell Recall, each time you cast a spell with a spell slot of 1-4 roll a d4, and if the roll matches the spell slot it will not be spent, does statistically in 75% nothing. 
At level 19+, you have 13 spell slots of that level. If you use all 13 spells, this feature will recover 3 slots on average. This might be impactful if you get double the level 4 spells per day, but it feels awful to play and use by the nature of rolling the dice. Especially if compared to other Boons. 

The floor of the feature is 0 spell slots recovered - the ceiling is infinite level 1-4 spells. 

The Boon of Spell Recall always does something 100% of the time.

It gives you 25% chance of recovery any spell slot of level 1-4 everytime you cast one.

It’s not necessarily bad for a feat, but it can’t compete with the other epic boons.  By the time your level is high enough to take it, you don’t get much out of it.

I also think they overcomplicated it for no reason.  One of the unspoken but usually used design tenets of 5e is that higher numbers are generally better.  If they wanted a 25% chance of success, they should have just keyed it off rolling a 4.  There’s no benefit to keying it off the spell level, it just adds another thing.

I would take a regular feat over this awful epic boon all day, every day and twice on Tuesdays. My god this is bad. As a wizard there are only 2 epic boons in the PHB I wouldn't take over this hot garbage, and this is the wizard's recommended epic boon? This one needs an errata. Something like the Divination wizard's expert divination ability maybe? Or add the ability to double the amount of slots from arcane recovery, seeing as most of the boons have two effects to this boon's one? Even then I'll still probably take dimensional travel, fate or truesight. Let's see, misty step a million times per long rest without even using a bonus action (I'd never walk again), a mini but more controllable portent every single fight (divination, shmivenation), make an always valuable 6th level spell permanent and undispellable -or- probably never recover a lowly level 1-4 spell slot you just cast when you really need to? (At 19th level, would you ever really NEED to?) This is a no brainer. If it had a 75% success rate it'd at least be on par with every other boon, as it stands now it's just an insult.