Is it just me or anyone having the same issue ?

My iPhone 12 Pro Max been over heating without using it and battery will go from 100 to 80 max , so can fix it replacing the battery? The battery health went from 94 to 89 in 2 months and I’ve has it since January!! I asked in fb and someone told me they have the same issues as me , also a YouTuber I follow who post about phones and said in a video he has a iPhone 12 Pro witch also went low in the battery health. Please help 😩