Not sure if this works...
But it sounds promising:
Linux: Prefer IPv4 over IPv6 in dual-stack environment (and prevent problems when only IPv4 exists) « SF-Alpha o_O! (bjgang.org)
Edit: TESTED and WORKS!
PING api.cloudflare.com(2606:4700:300a::6813:c01d (2606:4700:300a::6813:c01d)) 56 data bytes
64 bytes from 2606:4700:300a::6813:c01d (2606:4700:300a::6813:c01d): icmp_seq=1 ttl=57 time=254 ms
One single change in /etc/gai.conf file:
Take the "#" out from line: #precedence ::ffff:0:0/96 100
vi /etc/gai.conf
PING api.cloudflare.com (104.19.193.29) 56(84) bytes of data.
64 bytes from 104.19.193.29 (104.19.193.29): icmp_seq=1 ttl=54 time=6.44 ms