It's nothing critical but some ISPs use multiple layers of hacks to work IPv4 and certain types of networking become very unreliable over it. Things like long running connections will be dropped because the ISP routers do not maintain the NAT mapping forever.

For github pages its probably not going to make a huge difference but for things like SSH or file transfers it could be an issue. For things like video game servers or home servers you just flat out can not work them on v4 if your ISP uses CG-NAT.