We confirmed that the 60Hz version MODEL A2119 EMC 3279 works fine. The offending Apple dongle is MODEL A1621 EMC 2877 which is the obsolete model.
Please upgrade the Apple dongle to overcome the issue.
Adobe InDesign team
An error occurred while saving the commentBrett commented
I’m having a similar issue. In InDesign and Illustrator, my mouse lags like I’m dragging a block of concrete with it when the cursor is over the page or artboard, but no lag when the cursor is over a tools panel. Also, this only happens when using the programs on my external monitor, not on my MacBook screen. Tried a different mouse and same issue. The lag is so bad it makes InDesign and Illustrator unusable. 07/26/19
Adobe InDesign 14.0.2
Adobe Illustrator 23.0.3
MacBook Pro (13-inch, 2017, 2.3 GHz Intel Core i5, 8 GB 2133 MHz LPDDR3, Intel Iris Plus Graphics 640 1536 MB)
Monitor: DELL S2718D
Edit: I've also deleted and reinstalled my Creative Suite to try and fix, and still have the same issue.