I started a new  Survival World with the recent release of 1.14.1. After a couple of In-Game days I moved on close to a Taiga Village in a Mega Taiga Biome where I started to encounter with multiple Illager Patrols, they seem to commonly Pathfind close to my House since the Taiga Biome is just 50 blocks away, they come frequently from that side. 

So focusing on this, after kill 5 Illager Patrols Captains I found a weird Pattern in these Patrols. First off I found close to my Spawn Point a Pillager Outpost, a couple of times I went close to that place resulting in lot of Pillagers following my back since they seem to have a very wide detection range. Now the problem is that this logic doesn't apply to a Pillager that spawns inside an Illager Patrol, being both Pillagers and Vindicators these 2 Mobs can detect me from a normal distance but they only focus on the Player without moving or show any sign of try to approach me, unlike the Behavior that you will find in a Pillager Outpost or a Woodland Mansion that in the exact moment they see a Player they start Pathfinding towards them.

I took some Screenshots from my Survival World to display how this is happening.

 Here I was fishing when I got surprised, when I turned my back I found out these Mobs were only staring at me and not reacting or trying to reach me.

I tried to get closer and still the same Behavior

Until I got close enough to make them react, notice how here the Pillagers started charging their Crossbows and not previously, even when they could detect me thanks to their wide Range

Casually, it didn't took me a lot of time to find another Illager Patrol close to my Home and here I approached to take more time testing their AI

Notice here that my Game is not freezing or anything, it's runing regular. This is the average of FPS for me without Optifine.

Trying to move around in different directions, they still focusing on me but there's no sign of try to get closer and attack me.

In this side the Pillager is very close to me and it's not even charging it's weapon, I can't tell how close I am, but from my guess I am like 11 Blocks away from it.

• Now check the Coordinate Z: I am at 44
  

• I moved just 1 Block, see the Coordinate Z: 43 now
  And this was enough to trigger the Pillager and make it get closer to 6 Blocks from me letting it approach me while is charging the Crossbow
  

Here for example, only one is attacking me, the other Pillager is not getting closer or charging the Crossbow

I had to get less than 10 Blocks close

But, there's another interesting observation that I found. Upon triggering their AI by getting very close they will remain the normal Behavior and will try to approach a Player like they were supposed to do in first place.
Here are some Screenshot from previous Patrols that shows this

In this one, as you can see the 3 Pillagers are running towards me

Here too, I was getting far away from this Vindicator but it didn't stop chasing me, even from the 10 Blocks that didn't trigger the AI previously to just try to approach me