The greek language structure of Mark seems to be cut off abruptly at the end. It doesn’t conclude the Gospel properly. It wouldn’t have made sense to end it here either as we know from Paul’s letters which were written before. The end of the Gospel of Mark was likely a call to respond, to do what the women were told to do.
Secondly, you even seemed to say so yourself that John was written more isolated from the synoptics, so if they were trying to “censor” out when making stuff up, why would he include her in his gospel in the first place?
Lastly, that’s assuming Marcan priority, which generally tries to presuppose that Matthew wasn’t an eyewitness account in the first place. The early church clearly records Matthew as being written first and Matthew being written by Matthew (keep in mind that the Gospels were widely circulated by then and they had already rejected forgeries under names such as Peter) and Marcan priority was only hypothesised in the late 18th century, yet is still quite debated. Athiestic Bible scholars like it because it is useful for them to explain away the Bible.