While many have jumped to Version 19, professional post-houses often "freeze" their workstations on a build like 18.1.4.0009 for several reasons:
Version 18 uses a specific database structure. Moving to 19 requires a permanent upgrade of the project library, which can be risky in the middle of a major production.
Even without the very latest AI features of Version 19, 18.1.4 includes the heavy hitters that defined the 18-series: