Mob spawning issues
We're getting a lot of complaints about too few mobs spawning on 1.14.x servers.
As you might already know, we reduced the default render distance on 1.14 and newer servers. It is correct that the reduced render distance has an effect on spawning behavior. However, it is not the reason why almost no mobs spawn.
Besides the performance problems, there are massive mob spawning problems in 1.14.x.
Currently, we know that all 1.14 versions except 1.14.2 have these mob spawning issues.
Therefore we recommend switching to version 1.14.2 or 1.15.2.
The corresponding bug report on this topic in the Mojang bug tracker can be found here.
While 1.14.2 has a better working mob spawning behavior, there are several problems with villages and villagers in this version.
These problems are also known and fixed in 1.14.4.
Yes, that means if you don't want to switch to 1.15, you either have to deal with broken mob spawning in 1.14.4 or broken villagers in 1.14.2.
In general, we recommend upgrading to 1.15.