Probability you'll find info seems low so ´I want to know' will not work I think.
Previously with P3 was stated Sony Exmor - but no info with P4.
Looks IMX377 type not branded, maybe to reduce cost and sub-manufactured in China. Not sure if it's really a Sony, or can be partly or assembled elsewhere. Might explain why DJI doesn't publish origin with P4.
Don't take this as obvious, just trying to get more info for you.