Aaron Ross Powell from Cato Institute writes about the always fragile "fusion" of conservatives and libertarians becoming increasingly severed. He refers back to Robert Nozik's observation that " Liberty disrupts patterns" as at least a partial explanation.
Conservative- preferred social patterns are disrupted by liberty So to maintain those patterns conservatives turn to authoritarian means , if not they loose their conservative values.
What are these conservative values? They generally include family values which mean a man-woman stable relationship,opposition to gay unions,opposition to abortion and a tending to endorse traditional female roles in society, allegedly based in and supported by biblical principles. Additionally conservatives endorsed a society that is largely managed and controlled by white anglo saxon men with opposition to encroachment by black and brown immigrants, preferring things as they once were or were thought to be at some vaguely defined prior time.
Progressive big government with its ever growing body of liberty limiting regulations is a common foe for conservative and libertarians with conservatives bristling at bureaucratic rules antithetical to conservative's preferred social norms and libertarian obviously promoting liberty.
Decisions once made by families and local governments have been shifted to state and then federal government as the locus of decision making, a development well described and critiqued by Thomas Sowell in his book "Knowledge and Decisions ". This central decision making shift is another common foe for conservatives and libertarians.
Arnold Kling offered a framework for considering the differences between the languages used by progressives,conservatives and libertarians Progressives tend to frame things as there being a battle between the oppressed and the oppressors, while conservatives see things as between civilization and barbarism while libertarians view matters as between liberty and coercion.
In answer to the title question-No Trumpian authoritarianism did not break the conservative-libertarian fusion as it was a fragile union to begin though arguably useful regarding certain issues but his rhetoric may have provided a effective rallying cry (MAGA) and gave the nativists' core of conservatism a person around whom to rally.
I believe the key insight in Powell essay is that liberty disrupts patterns and conservatives hold certain societal patterns to be important which are put at risk by liberty so conservatives have to jettison liberty to protect their values. In the terminology of Kling the issue framed for conservatives is barbarism versus civilization and sometimes liberty must be sacrificed to fight off barbarism.Quoting Powell " conservatives have to restrict liberty to retain their social and economic patterns.".