VyOS seem to suffer from iputils bug that sometimes displays 2 decimal places in ping roundrip time.
Quite likely older versions are affected as well.
$ ping 1.1 PING 1.1 (1.0.0.1) 56(84) bytes of data. 64 bytes from 1.0.0.1: icmp_seq=1 ttl=57 time=19.5 ms 64 bytes from 1.0.0.1: icmp_seq=2 ttl=57 time=16.7 ms 64 bytes from 1.0.0.1: icmp_seq=3 ttl=57 time=17.6 ms 64 bytes from 1.0.0.1: icmp_seq=4 ttl=57 time=17.3 ms 64 bytes from 1.0.0.1: icmp_seq=5 ttl=57 time=17.3 ms 64 bytes from 1.0.0.1: icmp_seq=6 ttl=57 time=16.2 ms 64 bytes from 1.0.0.1: icmp_seq=7 ttl=57 time=18.5 ms 64 bytes from 1.0.0.1: icmp_seq=8 ttl=57 time=16.10 ms 64 bytes from 1.0.0.1: icmp_seq=9 ttl=57 time=17.6 ms 64 bytes from 1.0.0.1: icmp_seq=10 ttl=57 time=22.9 ms 64 bytes from 1.0.0.1: icmp_seq=11 ttl=57 time=19.2 ms