The CA/B Forum has decided to reduce the length of time digital certificates can be valid. The change is a gradual reduction that I expect is designed to make manual certificate renewal more and more cumbersome and drive people toward automating certificate management.

Currently: 398 days although many vendors issue certs for one year.
March 15, 2026: 200 days. Increased renewal frequency means manual tracking and renewal becomes more challenging.
March 15, 2027: 100 days. Manual tracking and renewal is painful, but possible.
March 15, 2029: 47 days. Automation is basically a requirement.