https://arstechnica.com/gadgets/2018...ok-pro-models/

Apple quietly launched a new battery replacement program to help a "limited number" of MacBook Pro users. According to the program's webpage, some 13-inch MacBook Pros without Touch Bars may experience component failure that causes the built-in battery to swell. It's not a safety issue, but Apple will replace batteries on the affected laptops for free.
The company didn't provide details about which component inside these MacBook Pros could fail and cause the battery to expand. Affected laptops were manufactured between October 2016 and October 2017, and users can check to see if their device is eligible by inputting the device's serial number into the program's webpage. Older MacBook Pros and MacBook Pro models with Touch Bars shouldn't be affected.
If your device is eligible for the battery replacement program, you can either take your laptop to an Apple Authorized Service Provider or an Apple retail store to have it serviced. Authorized personnel may need to send the laptop to Apple's Repair Center for a few days, and you have the option to immediately send the device into the repair center yourself rather than going to a store first. Apple advises users to back up all data on their MacBook Pros and repair any other problems with the device before getting it serviced.