Steps

1. On a page with blocks a (children a1; a2 with child a2x), b, c, d, click a2x, then Shift+click b. The selection holds a2x and b.
2. Press Shift+Tab.

Expected

a2x moves up one level, to after a2 under a. b is already at the top level, so b, c and d stay where they are. Shift+Tab never moves a block deeper.

Actual

The page reads a (a1, a2, a2x, b (c, d)): b moves one level deeper, into a after a2x, and c and d, which were not selected, move 2 levels deeper, under b. With the setting "Logical outdenting" on, b still moves into a; c and d stay.

Cause

indent-outdent-blocks in deps/outliner/src/logseq/outliner/core.cljs outdents the selected blocks with take-while, which stops only at a block whose parent is the target parent. b sits above that level, so b is taken too and moved after a2. Default outdenting then moves the right siblings of the last moved block (b's old siblings c and d) under it.

Found with a model-based property test of outliner operations built as the UI builds them, replayed on upstream master 16c4ed1a0.