That cld be a a leak in the board or wires or solders problems. Cld be power transistors leaking current over rating in tge board.
Swap cable to see is it the other part , pc side board, faulty.
Or change power point maybe power point leaking. Power point wire lose, not screw tight, can cause sparks or poor contacts create heat to the casing.
Why does USB C adapter run so hot?