The LHCb detector, a single-arm forward spectrometer designed for the investigation of heavy flavor physics at the Large Hadron Collider (LHC), features one of the world’s largest and most radiation-exposed muon detectors. Throughout Runs 1 and 2 of the LHC, operating at an instantaneous luminosity of 4$\times$10$^{32}$ cm$^{-2}$ s$^{-1}$ this detector has exhibited remarkable performance, with a tracking inefficiencies at the level of O(1\%). Following a preliminary upgrade targeting off-detector and control electronics, a second upgrade has been proposed to maximize the flavor physics potential during the HL-LHC period. However, the higher instantaneous luminosity at Run5 and RUN 6 (L$\sim$1$\times$10$^{34}$ cm$^{-2}$ s$^{-1}$) makes it necessary to redesign the muon detector to preserve its high detection capabilities. Different sub-detector technologies have being considered to cope with the wide difference in particle rates between the innermost region and the outer one. The state of the art of the muon detector design for the LHCb Upgrade II is presented.