During a dracut run i get:

dracut: *** Including module: systemd ***
dracut: *** Including module: systemd-initrd ***
dracut: *** Including module: i18n ***
dracut: *** Including module: drm ***
dracut: *** Including module: plymouth ***
/usr/lib/plymouth/plymouth-populate-initrd: line 450: +: command not found
dracut: *** Including module: kernel-modules ***
dracut: *** Including module: kernel-modules-extra ***
dracut: *** Including module: resume ***
dracut: *** Including module: rootfs-block ***


File /usr/lib/plymouth/plymouth-populate-initrd contains:

448 PLYMOUTH_Font_PATH=$(fc-list |grep $(fc-match "$(echo $(grep "^Font *= *"
${PLYMOUTH_SYSROOT}${PLYMOUTH_DATADIR}/plymouth/th   
emes/`plymouth-set-default-theme`/`plymouth-set-default-theme`.plymouth | sed
-e 's/^Font *= *//'| awk 'NF{NF--};1'))" |awk     -F : {'print $1'}) |awk -F :
{'print $1'} | sort -u | head -n 1)
449 PLYMOUTH_TitleFont_PATH=$(fc-list |grep $(fc-match "$(echo $(grep
"^TitleFont *= *" ${PLYMOUTH_SYSROOT}${PLYMOUTH_DATADIR}/p   
lymouth/themes/`plymouth-set-default-theme`/`plymouth-set-default-theme`.plymouth
| sed -e 's/^TitleFont *= *//'| awk 'NF{NF    --};1'))" |awk -F : {'print $1'})
|awk -F : {'print $1'} | sort -u | head -n 1)
450 +
451 [ -f "${PLYMOUTH_Font_PATH}" ] && inst ${PLYMOUTH_Font_PATH} $INITRDDIR
452 [ -f "${PLYMOUTH_TitleFont_PATH}" ] && inst ${PLYMOUTH_TitleFont_PATH}
$INITRDDIR


line 450 contains a single '+' ???? Clearly someone made a type.

I did find bug 1195600 which is about line 451, so probably related.

I'm running Leap 15.4 and

$ rpm -qf /usr/lib/plymouth/plymouth-populate-initrd
plymouth-dracut-0.9.5~git20210406.e554475-150400.3.5.1.noarch