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I was also wondering whether it's fine. It still can move about as you can see that there is a difference in position between the first and the second pictures, but it's not a wide movement indeed... as if it's having a cozy time on the leaf.
If it's a brown leaf, one could say that it's trying to conceal itself, but it's a green leaf so this reason is rather not making any sense so... no idea.

As it is in the picture, it would make a rather tasty and obvious meal for a predator, unless it is toxic and native species know that.