Google’s John Mueller confirmed that the search company’s 2014 guidance with faceted navigation remains true today – do not use non-standard URL encoding. That means do not use commas, brackets or other non-standard URL encoding in your URL structure.

Instead, use ampersands, equal signs, hyphens or other supported and standard URL encoded URLs for your fascinated navigation. This guidance is listed in Google’s blog post from 2014, here is a screenshot:

John said on Twitter it is “still a bad idea” to use non-standard URL encoding for this purpose:

I still see many sites using these methods – I wonder why…

Forum discussion at Twitter.