It has Alt+Shift+R assigned by default. Triggering it just causes the blending mode combobox to switch to "Normal", or blank if it was already in "Normal".
I can confirm this for the July 12 5.0.0-prealpha (git 6010423) and 4.4.5 appimages on Debian 10.
Git commit e2d6818840ffb95480a97ba5509095d47f8f4f47 by Wolthera van Hövell, on behalf of Alvin Wong. Committed on 14/07/2021 at 14:30. Pushed by woltherav into branch 'master'. Update blending mode hotkeys Adds: - G: Lighten - H: Hard Light - N: Normal - P: Hard Overlay Removes: - R: Normal -- It is for "Clear" which does not actually exist M +4 -1 reference_manual/blending_modes.rst https://invent.kde.org/documentation/docs-krita-org/commit/e2d6818840ffb95480a97ba5509095d47f8f4f47