Fortunately, the posts of users whose accounts have been deleted remain available to view. However, I can no longer search for them. A search for "user:4032" yields nothing.
Is this a bug? Is there an alternative way to search?
It exists. You need to use SQL? for database of this site.
select id as [Post Link] ,body ,owneruserid ,ownerdisplayname from posts where ownerdisplayname = 'user4032'
Click Run query in the link below. ("japanese" should be a placeholder for this site. You may change it to any site you want to search)
(This question seems to have been asked over a decade ago, but it has been Viewed only "289 times" on Meta Stack exchange...)