Engine evaluating changing after making move suggested by engine I've noticed that the engine (Stockfish 9) evaluates positions as significantly better for white if the evaluation is performed while white is on the move. The difference is sometimes more than half a point.

Someone else has noticed this phenomenon, and anyone has an idea what the reason is (It's not run time, as I've let the engine evaluate above 26 PLY in both cases).

To clarify: The intention here is NOT the same position, just switching who's on the move. I will examplify by the start position. Imagine evaluating it and the engine gives +0.7 and gives the 1. e4 e5. Then you make the move 1.e4 and let the engine evaluate again, and now it gives only +0.2 and recommends 1.. e5.
There's nothing surprising here. Chess engine is not perfect, as you make a move the evaluation will likely change:


The engine now sees something not seen before
The engine can now search deeper
The engine's hash table has relevant entries


This's just how we play chess. Our positional assessment change as we make moves. If that's not the case, there's no need to play the game - we shout out win/loss/draw without making a move.

Hint: If you're using your engine for your game, you'll need to make some moves to get better assessment. Kramnik did that for his win against Aronian:


  The computer doesn’t show it at the beginning, but then once you put it in he starts to like it a lot. 


https://chess24.com/en/read/news/berlin-candidates-3-a-kramnik-immortal

Sorry, chess is a hard game.