If you're referring to Cloudflare, the "security check" is not a default setting. For some reason administrators love to use Under attack mode as a band-aid measure to reduce load on the host.
Or they'll (the site operators using Cloudflare proxy) make ill considered firewall rules like "If not Chrome, require security check".
Or they'll (the site operators using Cloudflare proxy) make ill considered firewall rules like "If not Chrome, require security check".