This depends on the ad network, and whether the data is available to them in a first-party context.
A walled garden network like Facebook will likely have no problem continuing to use their first-party data about their own end users to target ads. However, other networks that don't have their own store of first-party data for targeting won't have that option (for example, re-targeting campaigns where the audience was generated somewhere else and then imported into the network's system as a list of IDFAs).
Updated 9 months ago
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