Next word of alias to alias that end with is not checked for alias

[anonymous4feedb...@outlook.com]

Dear dir or madam,

For the following script:
alias a1='echo '
alias a2=a1
alias foo=bar
a2 foo
bash outputs ‘foo’, instead of ‘bar’.

GNU bash, version 5.1.16(1)-release (x86_64-pc-linux-gnu) on archlinux as 
windows subsystem for linux

Thanks.