There's quite a discussion about that further elsewhere in this thread. To me, the combination of vector-like thick lines with that background color, the characters having such mute expressions and there not being one actual optimist.

Others also pointed to the "weirdness" that is the lines of the characters' arms becoming part of the table, which I didn't notice at first.

Perhaps more importantly, it does not look like the "author" has "zero drawing skill", but actually knows how to make vector art, even if relatively simple. That makes the problems more glaring