This affects only macOS, I think.
If I look into .cabal/store, I see:

~/.cabal/store/ghc-8.10.3$ ls
Dff-0.4.0-e2417685                 n-0.4.1-98d17fa3
Dff-0.4.0-e6c8ed46                 nclsd-xcptns-1.0.3-7f7ef320
HTF-0.14.0.3-710f7bdf              ndxd-trvrsbl-0.1-9a7dbfcd
HUnt-1.6.1.0-74fb3e3f              ndxd-trvrsbl-0.1-ec48aff0
HsYAML-0.2.1.0-7c9cf1ca            ndxd-trvrsbl-nstncs-0.1-be410491
QckChck-2.14.2-3e204cf1            nrdrd-cntnrs-0.2.13.0-0b73c8ca
QckChck-2.14.2-605cea58            nrdrd-cntnrs-0.2.13.0-a7a57927
ShllChck-0.7.1-f3d01607            ns-trmnl-0.11-fcd1ff58
...

Seriously! The Grinch stole all the vowels.
I cannot help feeling trolled by cabal v2. (Which I am still trying to learn.)
#5399 (comment)
Apparently, removing the vowels should help the Mach-O linker with its space limitations.
https://github.com/typedrat/cabal/blob/638c78e790721566780dbf75a2e6f884ceafa970/cabal-install/Distribution/Client/PackageHash.hs#L137-L145
I feels I am on the C64 again. Sure this isn't an Easter egg?

Questions:

• Just how many bytes are saved by dropping the vowels?
• Does this measure guarantee that things will work? (How? And how does this fight super long package names?)
• Do thinks break without the measure?
• Is this a systematic fix of the problem?
• How does this weigh against the confusion of the users?

Odd.