MacBook's bottom bulging after only 3 years – swollen battery?

If the battery is bulging, this indicates a potential safety hazard. You should stop using the notebook, and take it in for service (mailing it in this condition would not be advised) as soon as possible.

It does not, by itself, indicate that there is some systemic manufacturing issue. If there were many reports that this was happening, one would suspect manufacturing or design issues (like there were many years ago with "butterfly-switch keyboards" on Mac laptops). I recall that there was one Android smartphone that had lithium battery issues that were so severe that the FAA banned it in both the passenger and cargo compartments of all U.S. flights.

In the case of MacBook Pros like yours, I haven't seen any reports of widespread battery failures. Even very reliable brands can have sample defects, and you might just be the unlucky one-in-a-million winner of a Bad Luck Lottery.

There is a list of current Apple Service programs.

Apple Service Programs - Apple Support

There is one battery recall program on the list. It's for some of the 15" MacBook Pros.

15-inch MacBook Pro Battery Recall Program - Apple Support

Your tag line indicates that you have a MacBook Air, so that program wouldn't apply to it.

vahagnfromyerevan wrote:

I’m very disappointed that my MacBook (bought in the U.S. just 3 years ago) is already having serious hardware issues. The bottom casing is bulging, and I suspect a swollen battery.

FYI, most Lithium batteries need to be replaced between 3-5 years.

A laptop this expensive shouldn’t show safety-related damage so early.

Apple does not consider a swollen battery to be a safety issue. In fact the only time Apple had a free repair program for a battery safety issue for a laptop is the one @Servant of Cats linked for the 15" MBPro 2015. For the now expired free repair programs Apple did have for swollen batteries, Apple never claimed any safety issue. Dell and other OEMs say the same thing. Here is a Dell article (sorry, in order to show the Apple article requires searching the Internet Archive's Wayback Machine, or for some of my Apple forum posts from several years ago where I provided links to those Apple articles.

https://www.dell.com/support/kbdoc/en-us/000128491/swollen-battery-information-and-guidance

Actually found one of my older posts with the Apple article:

Battery Recall Program - @HWTech - Apple Community

This seems like a manufacturing issue and a potential safety hazard. Anyone else experienced this? Did Apple offer a solution or repair for free?

All Lithium Batteries have the potential to swell. It is in their very nature.

I’m based in Armenia, and there’s no official Apple Store here, only resellers. This is very frustrating.

I imagine it is frustrating, but everything has a limited lifespan. Like I said earlier, Lithium Batteries typically need replacing somewhere around 3-5 years. Some may need replaced sooner.....others later.