5 minutes of googling didn't give me any answer so I want to open a discussion here: would more layers in NAND have any impact on the lifespan or data retention performance? Any reason to buy 64-layer SSD over 176-layer version? or vice versa?
This is a complicated question and something I've covered extensively on Reddit and on my discord. However, in general, more layers is better, but that "better" involves a series of trade-offs, such as: endurance, performance, density, cost, etc.
An example of endurance gains with layers would be Intel going from 64L to 96L on their QLC. Performance-wise improvements were pretty minor - see the 660p vs. 665p, keeping in mind SLC cache changes - while endurance went from 1000 to 1500 P/E (with LDPC ECC). Intel uses floating gate (FG) for their flash which emphasizes endurance and in fact will be used in the future for split-gate PLC+ as well.
Another, different example of endurance gains with layers would be Micron going from 64L to 176L, but this had multiple changes involved. While their 64L flash was rated for 1500 PE, their 96L was 2000 and later 3000 - they changed the geometry on the 96L (B27A vs. B27B) by reducing the block size which improves endurance. Then they changed architecture from FG to CTF (specifically, replacement gate or RG a la TCAT, like Samsung's V-NAND basis) and achieved 5000 PE with their 128L flash (B37R).
In general endurance does improve with layer count because while die density increases - that is, bits per surface area of the die - the amount of data per layer does not necessarily increase. There are multiple types of disturb - more than planar has - but the effective process and cell size is much, much larger, so most types of disturb are insignificant, and alleviated or mitigated in a variety of ways otherwise. In any case, there's also a splitting of layers with decks which helps mitigate issues with high aspect ratio etching for example (which varies retention by word line position). At the controller level, ECC may also improve, including by having larger codewords. There's also been improvements to SLC caching and in many other areas too many to write. Of course, many of these are separate from layer count. But there are improvements made to circuitry every generation, for example putting peripherals under the NAND (CUA).
If you're going for more layers, though, it's because of capacity (cost per GB), energy efficiency, and performance. Endurance is better as a side effect of more general improvements. Good example is SK hynix's 128L flash first seen in the P31. That drive is incredibly efficient, has very good performance, and scales up to 1Tb/die (2TB SKU recently released) all while being affordable. But, it likely also has improved endurance over at least their old architecture.