Illustration of the effect of the polarisation leakage correction in Planck-LFI at 28.4 GHz around the position of W43. Stokes Q and U maps are represented respectively in the top and bottom panels. From left to right, the panels respectively show the PR3 raw (un-corrected) maps, the PR3 leakage-corrected maps using our own implementation (see Sect. 4.4.2 for details), and the public PR4 corrected maps.