The Reddit search is very static. It only gives you exact term matches from the title and body of a post (mostly). The advantage is that all reddit posts are instantly indexed (findable).
The google search doesn't only search in the title and body, but also in the comments. It also finds synonyms and potentially even finds a post through link structures.
I would like to give alternative search engines a chance, but this topic is very much a niche topic and Google's indexing is (unfortunately) by far the best.
added: 6/26/2023 , modified: 8/4/2023