My Sim constantly wants to use chat on the Computer/Laptop

Have experienced the same thing . Does your sim have insider trait ?

Definitely is a new recent bug, specifically for sims with the Insider trait. But I have also noticed some sims practicing programming on their own and hacking autonomously even without much of a programming skill or an otherwise geek-related trait.

Pretty much every single one of my Sims is doing that constantly, with or without the insider trait. Most of them have done so for a while, even before the latest update. It's either that or troll some forum or other. It's really annoying at this point because it has become their default action when they have nothing queued up. 

Obsessive behavior like constantly using the computer is not a bug.  It's a combination of things.  Traits, Likes and Dislikes, Career, Sentiments, Lifestyles and NAPs along with other things that together, combine to make up your sim's personality.  Another thing that comes into play is how you play your sims.  That can affect what your sims want to do autonomously, probably more than you realize.

That said, I agree that some of things that sims do obsessively can get really annoying.  And there are some things that I think the devs could/should tone down.  But there are things you can do to counteract those behaviors.  You can adjust like and dislikes easily in CAS.  Lifestyles can be changed by having your sims do something a lot in a short time period over the course of a day or two and not letting them do what they were doing obsessively.  You can repeal NAPS that cause some behaviors.  To change things like traits, you'll need to use the cas.fulleditmode cheat to change those in CAS. (If you do and your sim has one or more Discovery traits, randomize them first then assign new traits.)  Sentiments can be changed by changing how you socialize with other sims during gameplay.  There are a lot of ways to at least minimize most of the obsessive behaviors.   

And then, there are a number of mods that allow you change most of the things mentioned above as well if you are a mod user.  

Back to computer use.  You can also assign computers to specific sims to keep the obsessive one locked out.  If they need to use it for work tasks, writing books, programming, etc. you can unlock it and when they are done, lock it again.  Although, you might have to reset those assignments later as they will sometimes reset to default when an update or new pack is installed.  You can also lock doors to keep a sim out of the room where a computer is located too.  You can also give each of your sims a laptop that's assigned to them and just drop it on a desk, dining table or countertop when they need to use it.  When done, drag it back into the sim's inventory.  The downside to that is that if the game uses them as an NPC later, they may pull them out to use them and the computer can be left on the lot when your sims travel out so when you go back to a household, the laptop will be missing so you have to buy them another one.

And the most effective thing you can do to stop all obsessive behavior at any given time without mods, is to turn off autonomy in Game Options.  It won't stop all autonomy though, especially for things from later packs, but it will stop a lot of it.    

Hope this helps.

Trolling online when they have no previous mischief skill is why I lock the computer for everybody in security settings and only unlock it when I want someone to use it. And even then, I have to watch that they don't stop what they're meant to be doing. It's not like herding cats at all - I know how to herd cats!