Different behaviour for 7.3 and 7.5.1
7.5.1 by default use seq, 7.3.1 don't use it by default.
Example vyos config
set policy community-list 100 rule 4 action deny set policy community-list 100 rule 4 regex '.*' set policy community-list 100 rule 1 action permit set policy community-list 100 rule 1 regex 11:121 set policy community-list 100 rule 2 action permit set policy community-list 100 rule 2 regex 22:222 set policy community-list 100 rule 3 action permit set policy community-list 100 rule 3 regex 33:323
FRR config for 7.3.1
! bgp community-list 100 permit 11:121 bgp community-list 100 permit 22:222 bgp community-list 100 permit 33:323 bgp community-list 100 deny .* !
Frr config for 7.5.1
! bgp community-list 100 seq 5 permit 11:121 bgp community-list 100 seq 10 permit 22:222 bgp community-list 100 seq 15 permit 33:323 bgp community-list 100 seq 20 deny .* !
Now the sequence doesn't match rules.