There is a video online that Netherrealm has posted with the screenshots and removed shortly after.
In this clip you can see clearly Sindel.
So she is confirmed, atleast as a background character.
https://twitter.com/silversagi/status/1667256779267362831?t=xeuK6IY1SQ2YCirnwEbS-w&s=19
And here is a picture:
https://twitter.com/ejdelrey/status/1667252402771185664?t=qXG_2_eIZLc_YHgv8TmlsQ&s=19
717313=Rain Can Be Found In The Graveyard
I have seen that too. Sindel I believe will be in the game but not as a main roster character. I think Sindel will find herself as a Kameo fighter in this game.