Manjaro Cinnamon seems to use, by default, lightdm-slick-greeter from Mint. I searched on the net and I found there is lightdm-webkit2-greeter(-theme) and web-greeter. Web-greeter seems to be more up to date (see AUR repository). The only thing is that I don’t know how to use web-greeter instead of the one proposed by default by Manjaro Cinnamon.
Do you have any advice ?