She clearly presents noble intentions, and even makes good on some of those intentions.

For your statement to be true, she wouldn't have fought to free the slaves of Mereen, nor would she have told the Unsullied they could leave if they so chose.

They fought for her of their own choices, and she earned their unyielding support in the process.

Her more selfish motives have been there since she got her dragons, and as you correctly stated, have been seeded this entire time.

That those selfish motives have reached critical mass does not change that she has also had noble motives throughout, because she has inarguably demonstrated the opposite to be true.

The tipping point to me is when Jon came to her she reached a point where she had a chance to break the wheel, she could have granted Jon his crown to forge a true alliance.

Instead, she took his crown, demanded fealty in exchange to fight an enemy that was a threat to all of Westeros, only to turn around and frame that as "Jon's war".

Up to that point, despite her selfish motives growing, there was a clear duality.