[Mika Pa]

It looks like it was apart of

Dropped support for QuickTime 7 era formats and codecs:

https://helpx.adobe.com/x-productkb/multi/quicktime7-support-dropped.html

It seems like ProRes 4444 is apart that legacy codecs they dropped support with newer releases (even though they mention support for ProRes in general).

Adobe continuously aims to keep up with the most modern workflows, support formats, and codecs broadly used across the professional film and video industry. As a result, Adobe will no longer support legacy QuickTime 7 era formats and codecs starting from the following product versions:

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April 2018 release of Premiere Pro CC (version 12.1)
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April 2018 release of After Effects CC (version 15.1)

April 2018 release of Adobe Media Encoder (version 12.1)

April 2018 release of Adobe Audition (version 11.1.0)

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