Check your Nextdns.io logs and see what gets blocked. Then add the blocked domain (or the whole root domain) to the Whitelist. The whitelist always overrides any blocklist entry.

On Apple devices it’s as easy as toggling a switch to temporarily disable it. Not perfect but easy enough. Still trying to figure out a similar solution on Linux...

They added a new setting recently to allow affiliate links like those used for tracking which might include this, try it out.

If your really want to use it you should try diving into what blocklist is causing the block OR whitelist the URL.