ALT The dead tree, which Luke has tried repeatedly to bring himself to destroy, seeing it as representative of the failure of the Jedi. The dead tree he's been focused on instead of the living young Jedi he is called to nurture. The dead tree, which burns in the shape of the Rebel Starbird, as Yoda reminds him that he has been overlooking "the need in front of [his] nose" and that he needs to "pass on what [he has] learned." And then when we see him next, he declares that he "will not be The Last Jedi" as he burns himself to rescue the Resistance, which is "reborn" (like a phoenix, a starbird). It's probably nothing.