That's too simplified of a view. Horkheimer and the early critical theorists were accidental relativists in that they criticized the scientific method for being too pretentiously "objective" when research directions and background assumptions were just imported wholesale from society and not examined with the same rigor as the specific claims under study. The goal would thus be to have truth be less in the eye of society. (I couldn't find a pithy quote to illustrate this, but you can get this sense from reading essays in https://cominsitu.files.wordpress.com/2019/07/max-horkheimer-critical-theory-selected-essays.pdf, particularly the first one.)

Unfortunately, the solution was exactly backwards: individual scholars (i.e. the critical theorists) were to embrace activism and break free of societal dogmas and lead society and science to a new more perfect place. Very idealistic. Very forgetful that most of the scientific method is about restraining our various cognitive biases when trying to do all that stuff. So, consequently, I haven't been able to find any flavor of critical theory that is not in practice epistemologically indistinguishable from relativism.

But "truth is in the eye of the beholder" is not an accurate account of the position of early critical theorists. Their position was "everyone has unexamined presuppositions which may lead them to think they have found truth when they hae not". (Because of their inability to form sound epistemology to get out of this situation, the observation does lead directly to relativism: "can't fix it--let's give up, everyone just has their own truth.")