Yandex Bot 403

I get these error messages from Yandex.
The main mistake is “When accessing the page, the robot received 403”
This error does not occur on all of our sites.
Here is the Yandex support answer
The page https://xxxxxx.xx was indeed excluded from the search, because earlier it responded to robot requests with HTTP code 403. The problem was relevant, for example, when visiting the robot 2020-05-26 01:32:04. To find out the causes of the problem, you can contact the administrator of your site. Now the error does not occur, the page will be freely indexed by the robot and will be able to return to the search with subsequent updates to the search base as they are crawled by the robot.

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