Discourse sometimes hangs on my reply submissions, with a lot of JS errors as `net::ERR_BLOCKED_BY_CLIENT`

Am I the only one who sometimes has issues with replies submission? It hangs and starts throwing errors in the console as:

Failed to load resource: net::ERR_BLOCKED_BY_CLIENT
2/presence/publish:1
Refused to set the document's base URI to 'https://discourse.django-cms.org/t/slug-uniqueness-not-checked/21/3' because it violates the following Content Security Policy directive: "base-uri 'none'".

And many others.

At first I thought that it would be about my privacy addons, but I’ve disabled them for this website long time ago.