They should have used a cookie or something else that does not require asking me every few minutes to prove once more that I am not a bot.

There was a time when Cloudflare had become less intrusive, but for the last months it has begun again to intervene almost each time when opening some pages.

There is no doubt that anti-bot protection can be implemented in a better way than Cloudflare does, but presumably the alternatives would consume more resources on their servers, so probably they choose whatever minimizes their costs, regardless if that ensures maximum discomfort for Internet users.