Unfortunately, I couldn't find the official patch notes from Adobe. However, based on various sources, here are some of the issues that might be addressed in this patch:
Adobe Photoshop CC 2018 (Version 19.0.0) was a pivotal release for Mac users, serving as the last version to fully support and being the final bridge before Adobe moved exclusively to 64-bit applications with the 2019 release. The "Exclusive" 19.0.0 Context adobe photoshop cc 2018 1900 patch for mac exclusive
Always ensure your Mac has at least 20GB of free space to serve as a "scratch disk" to prevent "Scratch Disk Full" errors. Adobe Photoshop CC 2018 (19
: Unofficial patches often break core functions or cause frequent crashes. Official & Safe Alternatives Software Instability : Unofficial patches often break core