I see... I don't really know under what guidelines Pixiv works, but this is just plain out stupid from the website! So much to artistic freedom... That ending is simply to supposed to give the people who were unsatisfied with Ch.699/Ch.700 a satisfied ending
Hopefully, she can find another Japanese website that tolerates her alternative ending.
Just understand that my reply is merely a supposition based on my own suspicions. There's no official word yet as to why LadyGT's work was taken down.