grub2 serial console output on UEFI hardware ... inconsistent CR/LF behavior; starts & finishes OK, broken in the middle ... ?

[PGNet Dev]

i'm switching a server to UEFI boot -- and bumping into issues with serial 
console config

running

        grub2-install --version
                grub2-install (GRUB2) 2.04

        rpm -qa | grep ^grub2
                grub2-2.04-lp151.7.1.x86_64
                grub2-branding-upstream-2.04-lp151.7.1.x86_64
                grub2-i386-pc-2.04-lp151.7.1.noarch
                grub2-systemd-sleep-plugin-2.04-lp151.7.1.noarch
                grub2-x86_64-efi-2.04-lp151.7.1.noarch

with

        uname -rm
                5.5.6-24.g4a830b1-default x86_64

my grub config currently includes,

        GRUB_TERMINAL_OUTPUT="gfxterm serial"
        GRUB_SERIAL_COMMAND="serial --unit=0 --speed=115200 --parity=n --word=8 
--stop=1"
        GRUB_CMDLINE_LINUX=" ... \
         console=tty0 console=ttyS0,115200n81 \
         earlyprintk=serial,ttyS0,115200,keep"

connected to the serial console from a local desktop running 'minicom', output 
_does_ appear as expected.

formatting -- specifically carriage returns / line feeds -- however, _starts_ 
out OK, and _finishes_ OK once reaching the login prompt, and after.

but, in the 'middle', carriage returns go wonky ...

here's what I see in desktop's 'minicom' connected to server's serial port:

        https://pastebin.com/raw/KNB2JDHM

what needs to be configured to get the serial console to output consistently 
'well behaved' formatting from start of output to login prompt, and onward?