range.fill parsed the input once at the active cell, then put back the old
style of every target that already held a cell, so 5%, $5, 3/4/2026 or
=DATE(...) lost their automatic format there (0.05, 5, 46085), and empty
targets took the active cell's style. Each target now gets what
input_to_cell gives for it (parsed once per distinct style), as typing does.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>