Opera used to be a fantastic web browser, with a custom high-performance Presto rendering engine and features like tabbed windows that didn't show up in competing browsers until years later. However, the modern Opera browser is a shadow of its former self, reliant on chasing trends and meme advertising to
I remember that it was Google which intentionally made their sites non-functional with Opera. And that changing user agent alone was sufficient to make them work. I may be mistaken, of course.
EDIT: But yes, their developers were like that.