Alias in command substitution

[LitHack]

Normally declaring a alias inside the command substitution would not
reflect in main shell like........
lithack@aura:~$ `alias l=ls`
lithack@aura:~$ l
l: command not found
But using this command .....
lithack@aura:~$ `alias l=ls;alias`
lithack@aura:~$ l
 api      Desktop  Downloads      Music __py__      v      v.zip
 Arjun      dir  idafree82_linux.run      Pictures snap     vi
 BurpSuiteCommunity   Documents  'IDA Freeware 8.2.desktop'   Public
Templates   Videos
It runs in main shell. Is this a bug?

Note: This only works in bash shell.