Why is the encoding of preview links incorrect only on the iPhone and only on some pages?

Question

HTML

Why is the preview only on the customer's site and only on part of the site's pages? Everything is fine with me, the encoding for all pages of the site is the same, utf-8, the site is on WordPress. Incorrect pages on the client:

https://www.brg-consulting.ru/konsalting/finupr/ifrs/
https://www.brg-consulting.ru/its/tabs/vidiits/

although it is normally sent here, for example: https://www.brg-consulting.ru/its/consultant/

This is how he displays the first pages, which I indicated: