GIMP 2.10.14 has been released yesterday, and the releasenotes contain this paragraph (emphasis mine):
Improvements for the macOS version
Alex Samorukov introduced various improvements to the macOS build of GIMP.
First and foremost, GIMP is now compatible with macOS Catalina and doesn’t have the file permission issue that the 2.10.12 build had.
Secondly, the DMG will now open a window with an Applications shortcut that explains how to install it. He also added some fixes for command line users.
Finally, Alex built the new version with updated 3rd party components. Among other things, this means support for color profiles in HEIF/HEIC files.
Download is still in progress, but I really hope this has been fixed as announced.