@1outlaw3 This is a longstanding issue created by Opera's developers. They refuse to address the problem. There are workarounds. Some of these workarounds might help users of Manjaro running XFCE.
See the solutions offered in the following forum thread. One of them might work for you https://forums.opera.com/topic/28344/new-lack-of-opera-menu-bar-is-unusable/6?_=1590601136501