I have noticed a lot of confusion regarding backlinks in Google when people use the link: operator lately. A lot of people get worried if their backlinks have dropped in Google.
Google say "The query [link:] will list webpages that have links to the specified webpage. For instance, [link:www.google.com] will list webpages that have links pointing to the Google homepage. Note there can be no space between the "link:" and the web page URL."
Some people have read this to mean "Link: will list all webpages linking to the homepage", Which is untrue. The link: operator lists a small selection of links pointing to a page in no specific order.
If Google showed 200 links one day and 100 the next it doesn't mean they only know about 100 backlinks and it doesn't mean they have started ignoring half of your backlinks. The amount of backlinks Google shows depends on which datacenter you are querying with that search.
Google use all backlink in their algo as soon as they find them, Regardless how many links are displayed in a link: search.