Simple use of HOME with ${} instead of single $ sometimes doen't work... Ubuntu 22.04.3 LTS

[Etienne Lorrain]

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS: -g -O2 -flto=auto -ffat-lto-objects -flto=auto 
-ffat-lto-objects -fstack-protector-strong -Wformat -Werror=format-security 
-Wall
uname output: Linux etienne-7950x 6.2.0-34-generic #34~22.04.1-Ubuntu SMP 
PREEMPT_DYNAMIC Thu Sep  7 13:12:03 UTC 2 x86_64 x86_64 x86_64 GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 5.1
Patch Level: 16
Release Status: release

Description:
simple unmodified cut&paste of a session:

etienne@etienne-7950x:~$ /bin/bash --version
GNU bash, version 5.1.16(1)-release (x86_64-pc-linux-gnu)
Copyright (C) 2020 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
etienne@etienne-7950x:~$ /bin/bash
etienne@etienne-7950x:~$ echo ${​​​​​​​HOME}​​​​​​​:/home/${​​​​​​​USER}​​​​​​​
bash: ${​​​​​​​HOME}​​​​​​​:/home/${​​​​​​​USER}​​​​​​​: bad substitution
etienne@etienne-7950x:~$ echo ${​​​​​​​HOME}​​​​​​​
bash: ${​​​​​​​HOME}​​​​​​​: bad substitution
etienne@etienne-7950x:~$ echo $HOME
/home/etienne
etienne@etienne-7950x:~$ echo ${​​​​​​​HOME}​​​​​​​
bash: ${​​​​​​​HOME}​​​​​​​: bad substitution
etienne@etienne-7950x:~$ 
exit
etienne@etienne-7950x:~$ /bin/bash
etienne@etienne-7950x:~$ echo ${​​​​​​​HOME}​​​​​​​
bash: ${​​​​​​​HOME}​​​​​​​: bad substitution
etienne@etienne-7950x:~$ 
exit
etienne@etienne-7950x:~$ /bin/bash -l
etienne@etienne-7950x:~$ echo ${​​​​​​​HOME}​​​​​​​
bash: ${​​​​​​​HOME}​​​​​​​: bad substitution
etienne@etienne-7950x:~$ 

But sometimes it does work, cut&paste of another session:

etienne@etienne-7950x:~$ /bin/bash --version
GNU bash, version 5.1.16(1)-release (x86_64-pc-linux-gnu)
Copyright (C) 2020 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
etienne@etienne-7950x:~$ /bin/bash
etienne@etienne-7950x:~$ echo $HOME
/home/etienne
etienne@etienne-7950x:~$ echo ${HOME}
/home/etienne
etienne@etienne-7950x:~$ 
exit

Is there some kind of optimisation problem, and ${HOME} is treated as 
${/home/etienne} where obviously the error message "bad substitution" makes 
sense?
Is that often triggered by  the line "echo 
${​​​​​​​HOME}​​​​​​​:/home/${​​​​​​​USER}", double ${} on two different 
variables, but not always?

Repeat-By:

Sometimes I get the first behaviour (error message), sometimes the second 
correct behaviour (no difference in between $HOME and ${HOME})

The host is "AMD Ryzen 9 7950X 16-Core Processor" on Ubuntu 22.04.3 LTS (fully 
updated and fresh reboot this morning) and does not behaves incorrectly 
othewise, multiple hours compilations without any problems.