Why, periodically, Yandex requires captcha, supposedly requests are similar to automatic ones?

Question

Yandex

Greetings!
Recently, I periodically began to encounter the fact that Yandex issues "blah blah requests are similar to automatic ones."
But I have no idea what it's about. None of the reasons suggested in the articles on the topic seem to fit.
I assumed that this could be due to the fact that the dynamic ip that is currently available was a little earlier by another user who was doing something weird there, but no. 20 minutes ago, on the same ip, everything was perfectly searched without captchas, but after a while I make another rare request - and on you.
Tell me, what is this attack, what could be the matter?

Answer 1

you see, there are few IPs and
there are a lot of users,
so...

Answer 2

I was somehow pissed off when I used Wordstat, wrote to Yandex "yes, as much as possible, I'm already tired, I don't use automatic programs, I do everything manually", they kindly answered me "captcha was disabled on your profile. Well, I'm like that “And what was it possible to do that??” In general, they can chop it off custom on the account.