Is the corruption mentioned in the verse "And do not seek to cause corruption in the land. Indeed, Allah does not like corrupters" limited to merely advocating for artificial class distinctions (tribal, حضيري, صلبي, عبد) that prevent intermarriage between groups, or does it also include adhering to them despite knowing their violation of Islamic law and their role in corrupting society?

What is forbidden by Islamic law, it is forbidden to do it and to call to it. So, committing evil and calling to it is evil. However, calling to what is forbidden, while committing it, is more forbidden and sinful than merely committing the act; because in this case, the evil extends from its doer to others, and thus he bears his sin and the sin of those who follow him. So, whoever calls to misguidance will bear a sin equivalent to the sins of those who follow him, without diminishing any of their sins.