Interesting pick-up. Here's how I felt about it.Something that should be addressed :-
From Empire Strikes Back, as Luke is leaving Dagobah to save Leia and Han, Obi-Wan as a force ghost says to Luke, "If you choose to face Vader, you will do it alone. I cannot interfere."
From TLJ, Yoda, also as a force ghost, like Obi-Wan, manages to interfere in the physical world by causing lightning to strike the Jedi tree.
I've checked the lore, novels, Reddit, everywhere and can't find any mythology or history that documents the possibility of material interference in ghost form. That Yoda does this is jarring in as far as original trilogy faithfulness is concerned.
Personally I have always felt the force ghosts were just a manifestation of the force itself in a form that our characters will recognise. When we see Obi-Wan or Yoda as a ghost, it's the Force literally communicating to our protagonist through a persona. We're told a few times that these characters have become "one with the force" when they die, and I always took that fairly literally.
So when we get to Yoda striking the tree with lightning, I took that to mean lightning struck the tree because at that particular moment, that was the will of the Force. Yoda appears to do it because Yoda literally is the force now; they're one and the same. I'd even argue Luke takes it this way; after the tree burns he says "So it is time for the Jedi to end then", as though he takes it that the tree burning is the force trying to tell him something.
This may all simply be my headcannon, but I go back to the fact that those characters are said to become one with the force when they die.
tl;dr Yoda, as a force ghost, literally is a manifestation of the force. As such, Yoda didn't so much strike the tree with lightning as the force did.
So when we get to Yoda striking the tree with lightning, I took that to mean lightning struck the tree because at that particular moment, that was the will of the Force. Yoda appears to do it because Yoda literally is the force now; they're one and the same. I'd even argue Luke takes it this way; after the tree burns he says "So it is time for the Jedi to end then", as though he takes it that the tree burning is the force trying to tell him something.
This may all simply be my headcannon, but I go back to the fact that those characters are said to become one with the force when they die.
tl;dr Yoda, as a force ghost, literally is a manifestation of the force. As such, Yoda didn't so much strike the tree with lightning as the force did.