It might depend on the tech stack. I run a small niche website but it has PHP and a database (MediaWiki/PHPBB) and without Cloudflare I'd estimate I'd need to spend several hundred dollars a month to handle the traffic. Traffic used to be tens of thousands of requests a day. AI has increased that to between 400k and 3M requests per day but it's not a smooth distribution. This is with bot fight mode on that greatly reduces traffic.
I adopted Cloudflare because it was getting DDoSed by the AI crawlers. I'm pretty sure all of them are vibe coding their crawlers and don't bother adding rate limiting as a requirement.