My mac's battery is at 65% capacity.

Good evening,

For some time now, my macbook pro A1708 has become extremely slow. The activity monitor tells me that the system is using 80% of the processor and the fans are running at 7900rpm. It also shuts down randomly and sometimes it's just the screen going black for no apparent reason.

I reset it completely and installed a clean version of Monterey.

CoconutBattery tells me that the Design Capacity is at 65.8%, could my problem be due to the battery? My problems also persist when I'm plugged into the mains.

Thank you in advance for your feedback!