Can't stop snap baseline grid

Also, Baseline Grid—which you refer to in your title—is not the same as guides (Ruler Guides), and grids (Document Grid).

Here I’m showing the Baseline Grid (Light Blue), and my text is snapping to it because of the Paragraph setting Align to baseline grid:

If I Show Guides my Ruler Guides (Red) show, and the top of the text frame snaps to the Ruler Guides, but the text remains aligned to the basleine grid:

And then there is the Document Grid (set to Orange here), which the text frame can also snap to, but the text’s paragraph remains as Align to Baseline Grid:

Aligning text to grid is a paragraph attribute, so you have to check this either in the control panel, the paragraph panel or the paragraph styles panel if you use styles.