Here is link to the study (Rapid colonization of a space-returned Ryugu sample by terrestrial microorganisms) https://onlinelibrary.wiley.com/doi/10.1111/maps.14288

“The presence of microorganisms within meteorites has been used as evidence for extraterrestrial life, however, the potential for terrestrial contamination makes their interpretation highly controversial….

The long generation time, and growth and cell death stages of the bacterial life cycle suggest organisms under severe stress and strongly suggest these organisms are terrestrial contaminants. The removal by polishing and lack of reoccurrence of filaments confirms their terrestrial origin and implies contamination of only the upper few microns of the surface. The presence of terrestrial microorganism within a sample of Ryugu underlines that microorganisms are the world’s greatest colonizers and adept at circumventing contamination controls. The presence of microorganisms within space-returned samples, even those subject to stringent contamination controls is, therefore, not necessarily evidence of an extraterrestrial origin.”