This meme is trying to make out that the 6th logo is their current logo, but it isn't.
That's an icon often used by Mozilla as a whole (not their logo though), and doesn't feature the Firefox red panda/fox because it's not meant to represent Firefox.
Just so people know the 6th logo is Firefox's parent brand logo.
I hope the next Firefox logo is more stylized. I personally have like the 2013 logo the most but the first is a close second. Here is how the 2013 icon looks since it isn't on this list.
Personally the current logo is my favourite. The one you linked is too busy for me and all the detail gets lost and wasted when it's just an icon in the task bar or on the desktop or in the start menu. I also think the colours are a bit more cohesive in the current version, because while straight blue and orange usually go well together they're also over-used and in an icon like this it makes the components feel more separated and less like a unified logo. It also lends a glow to the fire on the fox.
I do agree that most of the detail gets lost. At least for me when the icon is smaller than 30x30~. I personally dislike the the simplification of the new icon makes it feel like it lacks any personality. I specifically miss the globe more then anything else. The globe made it feel like a web browser too me without it I wouldn't even known what it was the first time I saw it.
At less for me the newer two logos makes it feel more like a brand then a piece of software with a cute avatar.
I don't know how how to express my feeling and reasoning for my feeling into words.