Keyboard
In its everlasting pursuit to make things thinner, Apple redesigned its keyboard on the latest line of Mac laptops. They introduced a mechanism for its new, "Butterfly" keyboard, which is known to fail, and it's on its fourth iteration in 2019 laptops. It's supposedly better than earlier versions, but only time will tell whether or not it is.
Notable issues - dust and debris accumulates under the keys. Due to how thin the mechanism is, said debris gets lodged under the keys and prevents them from functioning properly.
Storage
Again, due to the pursuit of thinness, Apple chose to solder on its storage rather than let it be removable or upgradeable.
Models earlier than 2018 Macbooks have a connector inside, in case your laptop dies and you'd like to bring it in and get your data off. The latest models don't have this connector which means if your laptop dies for whatever reason, you can't disconnect your storage. Your data is gone with the laptop.*
Screen
Apple replaced the more reliable cable that connects the screen (in older laptops) with a thin, ribbon-like "flex" cable that has also undergone design iterations. It's said to be better on later models, but time will tell.
Read more
here.
* This doesn't affect the mantra that it's always a good idea to make regular backups. Everyone learns the hard way, sooner or later.
Verdict
I did a video on this and seems like opinions are split 50/50. Some agree with me and are waiting on Apple to fix these issues in a laptop design overhaul (new laptop rumored in 2020). Others think that the cumulative corrective design fixes that Apple has made are enough to deem the laptop reliable. It's too early to tell w.r.t the 2019 laptops.