Please try the following one by one:

Go to AdGuard's main screen and tap (Update Filters) in the right upper corner. Check if your problem is solved.
Go to SettingsSafari protectionUser rules and check if there are any rules that contain the problematic website's name. Disable them and check if it solves the problem.
Go to SettingsSafari protectionFilters and disable all filters to see if that will fix the problem. If it does, start re-enabling them one by one, checking after each filter if the website(s) are displayed as they should. This will help pinpoint the problematic filter.
If it's one of AdGuard filters, let us know about it by contacting support@adguard.com, and we will fix the problem.

Technical support:

PR and marketing:

Sales team

Support center

+1 844 907 4466
UK: 0808 178 7234
De: +44 20 3974 2348
Downloading AdGuard To install AdGuard, click the file indicated by the arrow Select "Open" and click "OK", then wait for the file to be downloaded. In the opened window, drag the AdGuard icon to the "Applications" folder. Thank you for choosing AdGuard! Select "Open" and click "OK", then wait for the file to be downloaded. In the opened window, click "Install". Thank you for choosing AdGuard!
Install AdGuard on your mobile device