At the start of the movie, Superman has just stopped an invasion. The fictional country Barovia, a US ally, has advanced weaponry and attempts to invade and annex a much smaller and poorer fictional country Jarhanpur which doesn't appear to have a military of any kind. Barovia is ethnically white (coded as Eastern European/Russian) and Jarhanpur is ethnically more middle eastern.

It is not a giant leap to correlate these countries to Isreal and Palestine, but really those superficial details are where the the similarities begin and end. There is no apparent religious connection to the invasion, nor terrorist activity. No ongoing tensions, direct involvement from the US goverment in the invasion, or any act of war or other event that triggers Barovia to invade. It is just a powerful country attacking a smaller country for their resources on the orders of a power hungry dictator. It's a trope that is not exclusively related to current events, that made as much sense 50 years ago as it does today. And the purpose of it in the film is to both critique Superman's naivete of geopolitics, and to reinforce his values that every life matters.

People that are mad about it and pretending that it is explicitly a depiction of the Isreali-Palestinian war are projecting meaning that isn't there, at least beyond maybe some subtext. It's always a bit telling when people see generic bad guys in a movie and think, "this is about me!" But, of course, if they felt that the depiction of the overwhelming military force against civilians made the Palestinians seem sympathetic to them... maybe they should think a bit more about why that is.