Enders Analysis senior media analyst Jamie MacEwan said: "The timing makes sense.
"Apple probably anticipates increased demand for exposure on the App Store. That's because Apple's iOS privacy changes have made other options less attractive."
Ad campaigns on other sites had less reliable measurements of success, he said.
And app developers ran ads only if they were sure the cost of winning new customers was lower than the amount they would spend on the app.
"As its ads business grows, Apple will have to make sure its execution on consent and privacy is impeccable" to avoid accusations of putting itself first, Mr MacEwan added.