Is 90 accuracy normal?
Your question has been answered (good post by KeSetoKaiba) so I'll just add some thoughts
First of all, 90-95% is not that high. It's an impressive score, especially at your rating, but won't raise alarms. In simple terms, accuracy reflects your play as compared to perfect play. I saw a recent game where you got a 91% score. In 32 moves (book moves don't count) you played 19 Best moves, with 6 excellent moves, 2 good, 3 blunders and 2 missed wins. You won't be mistaken for an engine or bot. Overall, your sub optimal moves where close enough to the best move to get a high rating.
Though 90%+ accuracy is impressive for a 600-700 player, it's is easy to score high against a 600-700 player. Because positions usually have obvious best moves. When your opponent makes mistakes, you get an easy best move.
I occasionally score around the 97, 98 or even 99% mark. Yet, no one will find it suspicious. Personally, I consider these my 'perfect' games. Opportunity presented itself and I took it. But to a higher rated player none of my moves would appear exceptional.
Meanwhile: Chess.com - 94.48% - Magnus Carlsen's average accuracy
Depends your level and game length. If you got a checkmate in like 7/8 moves or they resign, good chance you have 95+. In longer games, the chance of a higher accuracy decreases as there are more opportunities for you to make a mistake.
90 is obviously very good, but not uncommon. If you got 90 with like 40+ moves, I would say you are a very strong player.
Thanks for raising an interesting question. I have also wondered about this. I'm usually somewhere in the 70s/80s, but now and then a game with an accuracy in the 90s will occur. I assume that I just blindly stumbled onto a few good moves ... but KeSetoKaiba has shed a bit of light on the phenomenon.