Two-dimensional decomposition of the MW bulge in the [Mg/Fe]–[Fe/H] plane as a function of latitude based on the data inside 3.5 kpc from the Galactic centre. The left panels show the normalised stellar density maps, where the contours of different colours show the components identified using the 2D GMM approach. The grey histograms in the middle and right columns show the generalised [Fe/H]– and [Mg/Fe]–distribution functions, respectively. The coloured lines show the one-dimensional projections of the 2D-GMM components, while the black lines represent the sum of these components. In the middle row, the fractional contribution of each component is marked by the numbers of the same colour. Our analysis suggests that the [Mg/Fe]–[Fe/H] bulge composition is best represented by the five GMM components, where only two are the main ones and correspond to the bulk of high- and low-α populations. Two intermediate components allow for the decomposition of the transition between the main ones by fitting the α-knee and likely do not correspond to distinct bulge populations. The most metal-poor GMM component likely corresponds to the accreted populations.