John 8:1-11 are deemed to have been added several centuries after John’s penned this inspired gospel. Consequently, they are suspect and not all version/translations of the Bible contain them.
Regardless, considering your concern, it is suspect to me that this account does not mention, imply, accuse, and condemn the woman’s partner. The account also does not mention any partner discovered and accused. Have you considered this? Was she married? Was the participating partner married? Was she single and therefore actually guilty of committing fornication? Under the Mosaic Law, fornicators were not subjected to the same discipline under fleshly adultery.
Just as verse 6 states: “…they were saying this to put him to the test….” There are other scriptures where the scribes and Pharisees tried to put Jesus to a test with the intention to make accusations against him. In verse 7, Jesus was making a point of showing mercy. It seems to me that he indicated/implied that the accusers were may themselves have been guilty of adultery/fornication. The difference was that their conducts were not uncovered. Is it not the same in modern times? For example, is not a woman’s sexual misconduct is viewed differently than a man’s?