"script ran too long" out of combat
 

I'm pretty sure time limits were previously imposed on runtime only in combat, but nowadays I see reports of people seeing it on entering game with big on-demand loading addons like BigWigs or people running my Garrison Mission Manager with big followers list in WoD garrisons.

Did anything change while I was absent during BfA or with SL transition? Is there any official posts on that?

I was having problems with this during BfA and with BigWigs in particular.
I ended up splitting the bigger LoD packages into smaller pieces to deal with it, then wrote a preloader that would split the task of loading them over time on login instead of when you zone into an instance.