I contacted the author and he pointed to the "-a" option that controls the search behaviour. I found the "-A" option to follow my expectation of a forward and backward search,
-a or --search-skip-screen By default, forward searches start at the top of the displayed screen and backwards searches start at the bottom of the displayed screen (except for repeated searches invoked by the n or N commands, which start after or before the "target" line respectively; see the -j op‐ tion for more about the target line). The -a option causes forward searches to instead start at the bottom of the screen and backward searches to start at the top of the screen, thus skipping all lines displayed on the screen. -A or --SEARCH-SKIP-SCREEN Causes all forward searches (not just non-repeated searches) to start just after the target line, and all backward searches to start just before the target line. Thus, forward searches will skip part of the displayed screen (from the first line up to and including the target line). Similarly backwards searches will skip the displayed screen from the last line up to and including the target line. This was the default behavior in less versions prior to 441. I don't understand why the default behaviour needed to change. --