I happened to read a tweet by a Korean saying that he pronounces ‘무릎에’ (‘knee’/’lap’ + place marker) as [무르베], not [무르페].
I got curious so I searched Twitter. I found this tweet by 국립국어원 (The National Institute of Korean Language):
How to correctly pronounce ‘부엌을’ (‘kitchen’ + object marker) and ‘무릎에’ (‘knee’ + place marker)?
‘부엌을’ is pronounced [부어클] and ‘무릎에’ is pronounced [무르페].
I guess there are standard Korean pronunciation rules but native Koreans don’t always follow them. ###