A real leader still concerned about those she led with good intentions to their current really bad situation would declare the indentured enslavement contract with Alexis voided by the fact he is an obvious abusive evil douche. Especially when another opportunity such as helping the Inquisition close that minor skyhole that threatens everyone in Thedas.
They wrote Alexis as too abusive and evil to not question Fiona decisions especially when any other option was available.
There is a quaint shack with horribly murdered Tranquil skulls which alone is enough to say staying indentured to Alexis is most likely the worst possible decision.
Whether the change in Fiona is bad character writing, a failure of character under cumulative stress, magical character manipulation out of her control, or other head cannon reason is individual choice in RP.
It's not wrong for those who are okay or happy with Fiona's character in DAI. It's role playing and what you enjoy in game is the right answer.
For me I find Fiona in DAI to be another sad failed character like Orsino in DA2.
It's a way over played story in DA that almost every mage when stressed will choose the abomination, blood mage, harvester monster, and Venatori cultist path.
Should have been an option at Redcliffe to offer sanctuary to any rebel mages willing to leave their new Tranquil murdering employer Alexis. The pre-Quizzy only offers sanctuary to one Tranquil.
Why doesn't the pre-Quizzy have the option to provide sanctuary to at least the rebel mages they meet that want to leave their new evil master? Why doesn't the pre-Quizzy seem to care that there was a building with murdered Tranquil skulls?
Should someone judge the Quizzy when they are done judging Fiona? Teagan maybe?