I'm designing a timeline in which certain "event cards" are interactive while others are not. I'm running into a problem where the icons on the non-interactive cards look very dark, and therefore interactive, because I'm coloring them with the same HEX quality as the accompanying text ("PROMPT"), which is itself quite dark to conform to accessibility standards. My first inclination is to just make the icon color lighter (after all, it is a heavier weight than the text), but does that violate any rule that text/icon pairings need to be the same color? Really would appreciate any feedback here, thank you!
The simple answer is "no", as explained by others, but there's sort of an unasked question which is implied in your original description:
the accompanying text ("PROMPT"), which is itself quite dark to conform to accessibility standards
Normal color standards for accessibility require a 4.5:1 ratio. However, for elements that are inactive (ie, disabled), the contrast minimum is not required (but it is nice to try to keep the ratio to at least 3:1). So you can actually lighten up the color for "PROMPT" (and the icon too, if you want).
Icons do not have to be the same colour as the text. In fact, many UI designers choose a different shade of the text colour or even a contrasting colour for their icons, in order to balance out icons that would otherwise be too prominent or unnoticeable. The icon 'heaviness' usually dictates whether it should be darker (for thin line icons for example) or lighter (for thick icons).
Above all, your colour use should support a clear understanding of the current state and interactivity, rather than just following a blanket rule for each icon regardless of what it's purpose is.
I think that as you mentioned you can make the icon's color lighter without violating any rule. You could also reduce the icon's weight. In my opinion both could work.