Alt+Shift on Wayland doesn't update indicator, switches wrong layouts

Affected version

40.x (Wayland) on Arch Linux

gnome-shell 1:40.3-1
mutter 40.3-1
libxbcommon 1.3.0-1
xkeyboard-config 2.33-1

Bug summary

I have two basic keyboard layouts (us and lt) configured, and use Alt+Shift to switch between them (see below for exact list of options). In the past this used to work perfectly well, with both Xorg and Wayland, but suddenly I've noticed on this Wayland-using machine that pressing Alt+Shift

1. does not update the layout indicator in the top-bar,
2. cycles us → us → lt instead of the expected us → lt.

Steps to reproduce

gsettings set org.gnome.desktop.input-sources sources "[('xkb', 'us'), ('xkb', 'lt')]"
gsettings set org.gnome.desktop.input-sources xkb-options "['grp:lalt_lshift_toggle']"

My actual list of options is a bit longer, but it doesn't seem like the other options have any negative effect:

gsettings set org.gnome.desktop.input-sources xkb-options "['terminate:ctrl_alt_bksp', 'lv3:ralt_switch', 'grp:lalt_lshift_toggle', 'shift:both_capslock', 'eurosign:e', 'rupeesign:4', 'eurosign:5', 'compose:caps']"