Both the UI and the blocking functionality are broken in some searx 0.15.0 instances
Examples instances are search.snopyta.org, searx.libmail.eu, searx.remote-shell.net

And a couple of screenshots
https://i.imgur.com/FTivogl.png
https://i.imgur.com/PhOzh2L.png

Ungoogled Chromium 76.0.3809.132
ViolentMonkey 2.11.2
Script Version 2.1.0

Firefox: I added user includes in Violentmonkey for the three sites:

• https://search.snopyta.org/ => entire script seems to be blocked by CSP.
• https://searx.libmail.eu/ => entire script seems to be blocked by CSP.
• https://searx.remote-shell.net/ => entire script seems to be blocked by CSP. (Also no search results?)

Chrome: I added a user include in Tampermonkey for the first site:

• https://search.snopyta.org/ => the script runs, but inline style rules -- like display:none to hide the dialogs -- are blocked by CSP. What a mess.

It's not a quick rewrite to work around this, but I'll think about it for a future update.