Odds are, it means there's a depth* issue. In other words one of the two moves is better at low depth, and the other move is better at high depth.
Try it yourself - put the position into Lichess without a maximum depth and run Stockfish on it. You should find that Stockfish's best move changes as you let the engine run. It'll first suggest move X, then change its mind and say Y is better, and so on. For example, suppose you have
- d = 20: cxd4 (+2.01) Nxd4 (+1.80)
- d = 30: Nxd4 (+1.3) cxd4 (+0.9)
Now if the first screenshot uses only a d=20 search, while the second one uses a d=30 search, you'll get what you see: the first screenshot recommends cxd4, which the second screenshot calls an inaccuracy since it loses 0.4 centipawns.
If you're interested in this you might also want to check out this question. There's a good chance the computer will say on move nine that 8...Qh4+ is the best move, and then (after you execute it) say that 8...Qh4+ is an inaccuracy.
*Depth is a number that describes how far ahead the engine is searching. It is usually measured in ply, so d = 20 is 20 ply (or 10 moves) ahead.