The EDPB's Guidelines 8/2020 on the targeting of social media users stipulates that in order...

The EDPB’s Guidelines 8/2020 on the targeting of social media users explain that the legitimate interest legal basis requires passing three cumulative tests: the purpose test, the necessity test, and the balancing test. The purpose test checks whether there is a legitimate interest pursued by the data controller or a third party. The necessity test checks whether the processing is necessary for the purpose identified. The balancing test checks whether the legitimate interest is not overridden by the interests or rights and freedoms of the data subject. The adequacy test is not one of the three tests required by the legitimate interest legal basis. The adequacy test is relevant for data transfers to third countries, not for data processing within the EU.

References:

EDPB Guidelines 8/2020 on the targeting of social media users, Section 3.2.11

GDPR Article 6(1)(f)2

GDPR Recital 472

IAPP CIPP/E Study Guide, Chapter 3, Section 3.2.23