CSS temporary hack:
.discourse-adplugin .google-adsense-label>h2 {
font-size: 0;
}
.discourse-adplugin .google-adsense-label>h2:after {
content: "Foo bar"; // <--- change to whatever word you want to use instead of ADVERTISEMENT
font-size: 12px;
}
Before:
After:
Might not cover everything.