I was also not quite aware of such feud! I generally assumed that Poles and Lithuanians got along pretty well, or at least that was my impression from talking to Poles. Some time later I asked two Lithuanian guys what's up with this, what I saw as, asymmetric feud, and they explained that it may be in part due to some communities in the Polish minority in Lithuania, which were rather pro-Russian. Needless to say I was told that many years before the war in Ukraine, way before 2014 (no idea how the perception is now). This really perplexed me to the point where I permanently gave up understanding this kind of feud/friendship generalisation -- not only this stuff is extremely local, region-wise, and in the long run, it just does not hold up.