There are claims that something suspicious happened, but nothing has been proven.
A very large amount of oil trades, around $500–580 million, happened just before Donald Trump announced a delay in strikes on Iran. Right after that announcement, oil prices fell sharply, meaning those traders could have made big profits in minutes. Because of the timing, some people think it could be insider trading. But officials have denied any wrongdoing, and there is no clear evidence that anything illegal happened.
The timing looks unusual and has raised questions!