Password policy has been the default since MX21: https://mxlinux.org/blog/mx-21-wildflower-released/
It can be changed in MX Tweak.
ADDED: post #2 already gave you this advice.
after upgrade to MX23: password policy has changed
Re: after upgrade to MX23: password policy has changed
Desktop: Intel i5-4460, 16GB RAM, Intel integrated graphics
Clevo N130WU-based Ultrabook: Intel i7-8550U (Kaby Lake R), 16GB RAM, Intel integrated graphics (UEFI)
ASUS X42D laptop: AMD Phenom II, 6GB RAM, Mobility Radeon HD 5400
Clevo N130WU-based Ultrabook: Intel i7-8550U (Kaby Lake R), 16GB RAM, Intel integrated graphics (UEFI)
ASUS X42D laptop: AMD Phenom II, 6GB RAM, Mobility Radeon HD 5400