Random related data point: for HTTP requests to Wikipedia (and related) for the past 7d, the IP protocol split is roughly 35% IPv6 / 65% IPv4. (this is counting by-request, so heavy usage from a small number of IPv4s can skew it).
If be curious to see what the IPv4/IPv6 breakdown looks like when looking at HTTP/2 and HTTP/3 connections only, which should exclude the vast majority of crawlers.
