2.99.15 MacOS radio button menu items not proper, throw warnings, lock up
Image>Mode radio buttons do not have icons indicating they are radio buttons and which is active. Choosing RGB throws a warning from Gimp paraphrasing "radio button group does not have an active item". Sometimes a debug window and locks up.
On a self-built Gimp, using a Macports Portfile derived from the official one, on MacOS 10.13 (High Sierra old) and 12.6.5 (Monterey fairly recent.) Not the official build. The repo pulled a few days ago, so with recent GTK3 menu changes.