2 big address block that have few chances of conflict:

- CGNAT 100.64.0.0/10

- "Benchmark" 198.18.0.0/15

CGNAT is used by Tailscale and presumably in the wild for its intended purpose.

And `100.115.92.0/23` is used by ChromeOS for PatchPanel: https://chromium.googlesource.com/chromiumos/platform2/+/mai...