I've got no evidence except anecdptes, but I've heard claims that GoDaddy used to do this a lot. For this reason I've only searched a domain I was going to immediately buy, otherwise I'll do a whois lookup to see if it's registered.

Just looked about and found these:

"Does GoDaddy register domains you search?" (2011) https://news.ycombinator.com/item?id=2326790

Within this, was the comment that reminded me which company it was I was talking about (https://news.ycombinator.com/item?id=2327152) - Network Solutions used to do this - and there is a Wiki link in there which gives the process a name! TIL! :)

https://en.wikipedia.org/wiki/Domain_name_front_running

I remember something about registrars doing this so the domain you wanted wouldn't get snatched by someone else while you were in the process of buying it. Made more sense back in the time when far more basic names were available and such collisions were probably common for high-value domain names. Now it's two people finding the same needle in a haystack.

I knew a guy named pachell that did this from 1997-2001 until registrars changed the rule. pachell wherever you are, i miss you