Are a district court's findings on habeas abandonment subject to clear error review?

QUESTIONS PRESENTED 1. Are a district court’s findings that a habeas corpus petitioner’s attorney abandoned him “from the beginning” and “for the entirety of [his] state habeas application process” factual determinations that “must not be set aside unless clearly erroneous,” Fed. R. Civ. P. 52(a)(6), like the findings supporting the “cause” determination in Amadeo v. Zant, 486 U.S. 214, 222-224 (1988), or, as the Fifth Circuit held in this case and others, may a court of appeals review de novo all matters related to a finding of “cause”? 2. Do the Fifth, Third, and Seventh Circuits correctly apply this Court’s equitable “cause” doctrine when they hold, as a matter of law, that incompetence due to a brain impairment cannot excuse a procedural default because “mental incompetency ... is not a cause external to the petitioner,” Gonzales v. Davis, 924 F.3d 236, 244 (5th Cir. 2019) (per curiam), or do the Fourth, Sixth, Eighth, and Ninth Circuits apply the correct rule in holding that a habeas petitioner may excuse his default by showing it was caused by mental incompetence because the effects of a disease “cannot fairly be attributed to’ the prisoner,” Davila v. Davis, 582 U.S. 521, 528 (2017) (quoting Coleman v. Thompson, 501 U.S. 722, 753 (1991))? i