The important thing to note here is that these endpoints were scheduled for retirement at future dates; some in July 2018, some in Dec 2018. Today, with no prior announcement, these endpoints were abruptly retired.

Instagram had previously published a deprecation schedule for these endpoints, and threw that schedule out the window without notifying even Instagram Partners.

Edit to add: these endpoints are all related to the profile data and behaviors of non-oauthed users. This is the exact data that ML researchers (myself included) would normally use to analyze social graph behavior, interests, and audiences of Instagram users, and also is exactly the type of processing activity that GDPR restricts by requiring explicit and revocable consent. I see the abrupt retirement of these endpoints as a reaction to the pressure FB is facing as of late. This is a positive for personal privacy and will reduce the potential for abuse, however many types of legitimate and responsible businesses will be affected as well.