You're conflating left-wing social justice with left-wing economic policy. Zohran Mamdani is economically left-wing, and doesn't emphasise left-wing social policies, which I appreciate a lot about him. Left-wing economic policy is becoming more and more popular (and rightfully so) because it is about challenging the anti-democratic dominance of the Wealthy and Profit-Seekers in society. Left-wing social policy, on the other hand, is widely unpopular, with maybe the exception of abortion.
Also, when did Marx ever say anything about free buses, government grocery stores, or rent controls? Utter rubbish. Free buses are fairly commonplace around the world, in many decidedly non-Marxist nations. Rent controls have been used many, many, times in New York city... by very non socialist mayors and governments.
'Tax whites' and 'anti-semitic comments'. What has 'taxing whites' got to do with anything? And as for 'anti-semitic comments', I see you have bought fully into the Islamophobic lies being peddled by right-wing figures with very dodgy records relating to Jews. They use narratives essentially copy-pasted from the agendas of anti-Semites and Nazis, and edit them for use against against Zohran. They call him 'The Other'. They call him 'A Jihadist'.
All of it is playing on people's fears, and all of it is nonsense.