Some sites not blocked, /etc/hosts
The hosts that are not being blocked successfully are probably already in your DNS cache.
Try clearing the cache using:
sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder

if you are on Big Sur (looks like you are), or:
sudo killall -HUP mDNSResponder

if you are running Catalina, Mojave, High Sierra, or Sierra.
You may also need to clear the browser cache.  For Safari, go to Safari -&gt; Preferences -&gt; Advanced and turn on &quot;Show Develop menu in menu bar&quot;.  Next, in the Develop menu, chose &quot;Empty Caches&quot;