Hi Christian,
Interesting, sounds like it could be a GDAL issue.
Does the gplates_2.3.1-beta.8_Darwin-x86_64.dmg build in this post have the same problem? That uses GDAL 3.7 whereas GPlates 2.3 uses GDAL 2.9 (as far as I can tell).
I tried creating a cloud-optimised geotiff (the same way you did) and importing that into GPlates 2.3 (on macOS 10.15). That worked for me though. If the above GPlates build still crashes feel free to send me the TIF that causes your crash.