Watch what the deflection changes
Under Law 9, a ball contacting a match official on the field can trigger a stoppage when possession changes, a promising attack starts or it goes straight into goal. Other incidental contacts can leave play continuing.
Suppose a team exchanges square passes near halfway. A pass brushes the referee but still reaches its intended receiver without changing the attacking situation. Compare a second version in which the ball ricochets into an opponent’s path and gives that opponent possession. The important difference occurs after the contact.
Do not turn the restart into a foul
A dropped ball in this situation is a way to restore play after interference. It does not mean the referee awarded a tackling foul against the passing team. That distinction matters if a compact graphic briefly displays a restart marker without explaining its cause.
On replay, follow the intended recipient, the actual recipient and the space opened by the rebound. Those three observations make the decision easier to understand than repeatedly watching the ball strike the official. Where the promising-attack condition is involved, the referee is making a judgment about the resulting situation, so a single still frame has limited explanatory value. The contact is visible; its consequence is the second part of the analysis.
Questions answered
Must every referee touch stop play?
No; Law 9 specifies consequences that cause a stoppage.
Is a dropped ball a free kick against the passer?
No. It is a different restart.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.