Source? Cloudflare did post a moderately hostile response to Tor a few years back, but their technical implementation is sound and does not present multiple CAPTCHAs to users who have cookies enabled (the CAPTCHA might be broken with JS off, but that's a Google problem).
Even I have seen CF captchas on multiple sites when using Tor. Though might be because of my usage pattern where I use Tor for a selective list of sites giving CF less chance to maintain my identity.
It's OK now, they no longer show a captcha on most websites behind Cloudflare.