I think there is a very good argument of antisemitism if you support Hamas. There is no argument for antisemitism if you support Palestinians.

Who the fuck supports Hamas? It's an actual terrorist organization that's oppressing people in Palestine

Colloquially yeah it makes a lot of sense to say Hamas is antisemitic, the word means hatred for Jews regardless of the etymology of 'semite'. Take it up with marriam-webster, not the people correctly using the modern definition of the word

it doesnt even make sense because by definition both parties are semetic.

Oof, either you're just grossly misinformed and performing a cringey "ackchually", or you're anti-semitic yourself and perpetuating anti-semitic rhetoric.

While yes, both are Semitic people, the term 'anti-semitic' was specifically coined by Nazi Germany to make their genocide seem like it had a basis in science. They specifically used it to refer to Jews. Nobody uses "anti-semitic" to mean all semites except hate groups and holocaust deniers who are trying to say "see, it doesn't even mean Jews specifically! Jews are just playing the victim!"

I will assume you're simply ignorant or misinformed, but feel free to correct me if this was actually an intentional dog-whistle.

Due to the root word Semite, the term is prone to being invoked as a misnomer by those who interpret it as referring to racist hatred directed at all "Semitic people" (i.e., those who speak Semitic languages, such as Arabs, Assyrians, and Arameans). This usage is erroneous; the compound word antisemitismus (lit. 'antisemitism') was first used in print in Germany in 1879[17] as a "scientific-sounding term" for Judenhass (lit. 'Jew-hatred'),[18][19][20][21][22] and it has since been used to refer to anti-Jewish sentiment alone.