Chatter Under Acceleration

New here. Wondering if I am hearing piston slap or something else? I have read the former is fairly common. The vehicle in question is 02 Outback Automatic. It is definitely more pronounced in the colder weather and does go away sometimes. I did not notice it being that pronounced before purchasing it fairly recently (of course) but do know that some chatter is not out of the norm for Subie engines. Thanks in advance.

check the oil