Looks like the capturing effect of the Myko-Mentori Breakthrough considers neutral planets to be the Myko player's planets and automatically captures enemy Infantry that die there (and sometimes Fighters, for some reason?).
#Myko Breakthrough captures units on neutral planets
magic hound
fair lionBOT
RomanSO used /search breakthroughs search: mykomentoribt
SYNERGY: 
Capture other player's infantry that are destroyed during combat on planets you control. After each round of ground combat on a planet you control, roll a die. On a result of 7 or greater, place up to 1 of your captured infantry onto that planet, as if it were your own.
young thistle
Fixed