GIMP-2.99 uses sRGB instead of the user-selected monitor profile
Since commit e09e563a GIMP-2.99 uses sRGB as the monitor profile regardless of the monitor profile chosen in Preferences/Color Management.
This means anyone not using a monitor calibrated to match the sRGB color space sees wrong colors. For example on my monitor (which can't be calibrated to match the sRGB color space, but has a larger color gamut than sRGB) especially greens are too saturated.
The commit message does say "TODO: the image's "enable color management" switch is currently broken, will fix that in another commit." But it's not clear whether this "TODO" refers strictly to user option to enable/disable color management by checking/unchecking "Image/Color Management/Enable Color Management" or also to the ability to use the monitor profile selected in Preferences/Edit/Color Management.