Why did “crocozybras” appear on the admin panel and only the header of the previously installed template was displayed?

Question

1C-Bitrix

After installing the template from the marketplace, I went to the site and saw a broken encoding on the Bitrix administration panel and only the header of the site was displayed.
Oddly enough, Cyrillic is displayed normally in the admin panel itself.

Note: Before this, there were coding errors identified during the system check. I fixed them, only after that I integrated the template.
How to solve this problem?