Steps

1. Give today's journal the blocks a, b, c, and yesterday's journal the blocks e, f.
2. On the Journals page, Ctrl+click a, then Ctrl+click e (Cmd+click on macOS).
3. Press Alt+Shift+Up (Cmd+Shift+Up on macOS).

Expected

Each block moves up within its own page, which here moves nothing, since a and e are the first blocks of their pages. A block never changes page on a move up.

Actual

e leaves yesterday's journal and lands in today's journal right after a, above b and c. Clicking e first, then a, moves a into yesterday's journal instead.

Cause

move-blocks-up-down in deps/outliner/src/logseq/outliner/core.cljs computes one target from the first selected block and moves the whole selection there. For a block at the top of a page, the guard (not= (:db/id (:block/page first-block-parent)) (:db/id left-left)) compares the page's :block/page, which is nil, with the page itself, so it passes, and the call moves every selected block to the top of the first block's page. The UI handler editor/move-up-down does not restrict the selection to 1 page.

Found with a model-based property test of outliner operations built as the UI builds them (Ctrl+click selections in any order), replayed on upstream master 16c4ed1a0.