Per Kayla's comment below, remove the extra 1px border under collapsed expandable rows.

Additional info from dupe #6667 (comment)

Double bottom-border on non-expanded rows in expandable tables. Here's where the borders are coming from

patternfly/src/patternfly/components/Table/table.scss

Lines 1060 to 1062 in c11387c

	.#{$table}__tbody {
	border-block-end: var(--#{$table}__tr--BorderBlockEndWidth) solid var(--#{$table}__tr--BorderBlockEndColor);
	}

patternfly/src/patternfly/components/Table/table-grid.scss

Lines 185 to 188 in c11387c

	// - Table grid not expandable row
	tr:where(.#{$table}__tr):not(.#{$table}__expandable-row) {
	border-block-end: var(--#{$table}__tr--responsive--border-width--base) solid var(--#{$table}--responsive--BorderColor);
	}