I found error in firefox browser only:
Notice: Undefined offset: 0 in /home/unisystem/domains/unisystem.cfolks.pl/public_html/wp-content/plugins/toolset-blocks/application/models/WooCommerce/WcQuery.php on line 428
Thank you for contacting us and I'd be happy to assist.
There are two different issues involved:
1. The error shown in the screenshot is originating from a script file loaded by Astra's add-on for WooCommerce:
I see this error in the browser's console when visiting the shop page not only in Firefox but also in Chrome.
I'll recommend testing the shop page, with only Toolset plugins active, and once confirmed that this shows only when Astra's add-on plugin is activated, it would be best to report this to Astra's support.
2. The 'Notice: Undefined offset: 0' is something that is already reported.
It shows when a WordPress Archive is being used for the product and product category archive and secondary sorting order is also set.
( screenshot: hidden link )
Using the secondary sorting option in this particular case results in this warning notice and the incorrect sorting of results.
I'll keep you updated on the progress of this issue through this ticket and for now, it would be best to not use the secondary sorting for this "Katalog Produkty" WordPress Archive.
I hope this helps and please let me know if you need any further assistance around this.