The jury is still out
People do not yet know the answer or have not decided on an issue
e.g. There’s not enough evidence to say whether the increased vulnerability of Asians to Covid-19 is genetic or sociological (deprivation, living conditions etc); the jury is still out on that.
The idiom draws from when a jury of peers retires to decide the outcome of a court case. They jury is “out” and they come back “in” to deliver their verdict.