run the shell command with -exl options and got more details.

$ /bin/bash -exl /tmp/jenkins14350390494263487133.sh
+ '[' '' ']'
+ '[' -d /etc/profile.d ']'
+ for i in /etc/profile.d/*.sh
+ '[' -r /etc/profile.d/01-locale-fix.sh ']'
+ . /etc/profile.d/01-locale-fix.sh
+++ /usr/bin/locale-check C.UTF-8
++ eval
+ for i in /etc/profile.d/*.sh
+ '[' -r /etc/profile.d/apps-bin-path.sh ']'
+ . /etc/profile.d/apps-bin-path.sh
++ snap_bin_path=/snap/bin
++ '[' -n /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games -a -n /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games ']'
++ export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
++ PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
++ '[' -z '' ']'
++ export XDG_DATA_DIRS=/usr/local/share:/usr/share
++ XDG_DATA_DIRS=/usr/local/share:/usr/share
++ snap_xdg_path=/var/lib/snapd/desktop
++ '[' -n /usr/local/share:/usr/share -a -n /usr/local/share:/usr/share ']'
++ export XDG_DATA_DIRS=/usr/local/share:/usr/share:/var/lib/snapd/desktop
++ XDG_DATA_DIRS=/usr/local/share:/usr/share:/var/lib/snapd/desktop
+ for i in /etc/profile.d/*.sh
+ '[' -r /etc/profile.d/bash_completion.sh ']'
+ . /etc/profile.d/bash_completion.sh
++ '[' 'x5.0.17(1)-release' '!=' x -a x '!=' x -a x = x ']'
+ for i in /etc/profile.d/*.sh
+ '[' -r /etc/profile.d/cedilla-portuguese.sh ']'
+ . /etc/profile.d/cedilla-portuguese.sh
++ '[' '' = pt -a en '!=' pt ']'
+ for i in /etc/profile.d/*.sh
+ '[' -r /etc/profile.d/gawk.sh ']'
+ . /etc/profile.d/gawk.sh
+ for i in /etc/profile.d/*.sh
+ '[' -r /etc/profile.d/Z97-byobu.sh ']'
+ . /etc/profile.d/Z97-byobu.sh
++ '[' -r /usr/bin/byobu-launch ']'
++ '[' '' = 0 ']'
++ '[' '' = 1 ']'
++ '[' -e /etc/byobu/autolaunch ']'
++ '[' '' = byobu ']'
++ '[' '' = byobu-screen ']'
++ '[' '' = byobu-tmux ']'
+ unset i
+ '[' -n '5.0.17(1)-release' ']'
+ '[' -f /home/jenkins/.bashrc ']'
+ . /home/jenkins/.bashrc
++ case $- in
++ return
+ '[' -d /home/jenkins/bin ']'
+ PATH=/home/jenkins/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
+ exit 0
++ '[' 1 = 1 ']'
++ '[' -x /usr/bin/clear_console ']'
++ /usr/bin/clear_console -q
Build step 'Execute shell' marked build as failure
Finished: FAILURE

output of running same command on an ubuntu 18.04 node.

$ /bin/bash -exl /tmp/jenkins17283880185058389627.sh
+ '[' '' ']'
+ '[' -d /etc/profile.d ']'
+ for i in /etc/profile.d/*.sh
+ '[' -r /etc/profile.d/01-locale-fix.sh ']'
+ . /etc/profile.d/01-locale-fix.sh
+++ /usr/bin/locale-check C.UTF-8
++ eval
+ for i in /etc/profile.d/*.sh
+ '[' -r /etc/profile.d/apps-bin-path.sh ']'
+ . /etc/profile.d/apps-bin-path.sh
++ snap_bin_path=/snap/bin
++ '[' -n /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games -a -n /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games ']'
++ export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
++ PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
++ '[' -z '' ']'
++ export XDG_DATA_DIRS=/usr/local/share:/usr/share
++ XDG_DATA_DIRS=/usr/local/share:/usr/share
++ snap_xdg_path=/var/lib/snapd/desktop
++ '[' -n /usr/local/share:/usr/share -a -n /usr/local/share:/usr/share ']'
++ export XDG_DATA_DIRS=/usr/local/share:/usr/share:/var/lib/snapd/desktop
++ XDG_DATA_DIRS=/usr/local/share:/usr/share:/var/lib/snapd/desktop
+ for i in /etc/profile.d/*.sh
+ '[' -r /etc/profile.d/bash_completion.sh ']'
+ . /etc/profile.d/bash_completion.sh
++ '[' -n '4.4.20(1)-release' -a -n '' -a -z '' ']'
+ for i in /etc/profile.d/*.sh
+ '[' -r /etc/profile.d/cedilla-portuguese.sh ']'
+ . /etc/profile.d/cedilla-portuguese.sh
++ '[' '' = pt -a en '!=' pt ']'
+ for i in /etc/profile.d/*.sh
+ '[' -r /etc/profile.d/Z97-byobu.sh ']'
+ . /etc/profile.d/Z97-byobu.sh
++ '[' -r /usr/bin/byobu-launch ']'
++ '[' '' = 0 ']'
++ '[' '' = 1 ']'
++ '[' -e /etc/byobu/autolaunch ']'
++ '[' '' = byobu ']'
++ '[' '' = byobu-screen ']'
++ '[' '' = byobu-tmux ']'
+ unset i
+ '[' -n '4.4.20(1)-release' ']'
+ '[' -f /home/jenkins/.bashrc ']'
+ . /home/jenkins/.bashrc
++ case $- in
++ return
+ '[' -d /home/jenkins/bin ']'
+ PATH=/home/jenkins/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
+ exit 0
++ '[' 2 = 1 ']'
Finished: SUCCESS

wrong $SHLVL cause the error?

this should be a bug of ubuntu.

https://askubuntu.com/questions/1267095/shell-level-issue-on-ubuntu-20-04