As if the M272 didn't have enough of a bad repuation for :

(a) Balance shaft sprocket failure and associated timing chain failure.
(b) Cam plug oil leak

It seems that there was an OEM source who provided Big End bearings which were slightly too undersized. Latest engines run very hot for reduced emission control. The hot engine feature causes the faulty big end bearings to expand a little. Engines with these bearings produce a sort of Donk Donk noise for a few seconds after cold start up.
Repair is engine out, sump off and replace with better tolerance units.
This is a pot luck problem. You will be unlucky if you have an engine with this issue.