m4v3rick
I found the solution, it is very simple :
edit the file : vendor/justoverclock/last-tweet/js/dist/forum.js
Find these characters : app.forum.attribute("justoverclock-last-tweet.theme")
And replace them by : getComputedStyle(document.documentElement).getPropertyValue('color-scheme')
Disable then enable again the plugin, or clean the cache, and that's it !