The "AND" operator is unnecessary

[Matt_James]

kw1 kw2 kw3 gets different search results to kw1 kw2 and kw3. I have never noticed this before, is it new since the update?

[vitaplease]

IMO, the "and" is seen as a "common word" and not as an "operator".
It is ignored, but the proximity of the search words in your query have changed.

Therefore you see different results.