There are about 70k routes in the current DFZ. It's time to increase VyOS's default…? But as someone who has encountered "issues" with the potential for kernel resource exhaustion by IPv6 routes — https://www.youtube.com/watch?v=R0INwMN6FFE — I would exercise caution against setting it to something inappropriate.

And maybe it's worth reconsidering whether sys.net.ipv4.route.max_size having the humongous value of 2147483647 is sane. At least with IPv4 (and with more recent kernels for IPv6) you can't grow the routing table size without bound by scanning network address-space :)