The sniff we're using for the alphabetical use order from psr2r-sniffer compares use statements with direct string comparison. This means that the order is expected to be:
use A;
use const A;
use D;
use function A;
use G;
This doesn't really make much sense. The slevomat standard instead sorts classes, then functions, then constants (you can flip the last two via config).
We should look at switching to this, and clarifying the order in the handbook; if we instead want (e.g.) constants, then functions, then classes, we may need to fork it.
(Side note: there are some neat other sniffs in their standard we could incorporate.)