Battery Replacement
What battery for MacBook Pro (Retina, 15-inch, Mid 2015)?
MacBook Pro 15″, macOS 11.5
Question marked as
Have Apple or an Apple Authorized Service Provider examine the laptop to provide you with a repair estimate to replace the battery. The quality of third party Lithium-ion Batteries is extremely poor even when purchased from a reputable vendor. Besides with the Apple battery replacement you will also end up with a new keyboard and trackpad since all three parts are part of the larger Top Case Assembly. Apple just recently changed their procedures to allow for an official battery replacement for up to 10 years.
You should have Apple or an AASP examine the laptop in case it qualifies for the Battery Recall in which case you may even get a free battery replacement from Apple, however, only a small number of laptops will be affected by the battery recall program.
https://support.apple.com/15-inch-macbook-pro-battery-recall