When exporting as TIF each layer should have a color profile attached
This came up in issue #4176 (closed). Currently we only store the color profile with the first page (is bottom most layer in GIMP) and omit a color profile for all other pages (all other layers in GIMP).
Since TIF images consist of pages, not layers, and each can have their own color profile. It is probably a good idea to attach the color profile used in GIMP to each TIF page.
This way for any image viewer or editor there will be no ambiguity about what color profile to use.