The website has disallow rules for Ahrefs Bot.
https://ahrefs.com
Robots.txt
Get access to data on 5,039,717 websites that are Ahrefs Bot Disallow Customers. We know of 3,552,907 live websites using Ahrefs Bot Disallow and an additional 1,486,810 sites that used Ahrefs Bot Disallow historically and 2,195,320 websites in the United States.
Get a list of 5,039,717 websites using Ahrefs Bot Disallow which includes location information, hosting data, contact details, 3,552,907 currently live websites and an additional 1,824,135 domains that redirect to sites in this list. 1,486,810 sites that used this technology previously and 2,195,320 websites in the United States currently using Ahrefs Bot Disallow.