The Dangers of the phrases:
"Free Palestine" and
"From the River to the Sea"
These statements are political statements relating to land. Not calls for human rights.
The concerns with this rhetoric specifically are:
1) that it calls for the ethnic cleansing of Jews in Israel - literally "from the (Jordan) river to the (Mediterranean) Sea.
2) it is being used to perpetuate antisemitism, veiled as advocating for human rights.