Maybe it's because they still remember how things were under Fascism in the times of Franco.

Also there is quite the cleavage in Spanish Politics between a Fascists-turned-Democrate mainstream (plus actual Fascists, in the form of the Vox Party) and the old center-left (which like the rest of the mainstream in Europe have been moving ever more rightwards) which is currently in Government, so maybe there is a "Screw you Fascists!" factor that helped convince the party in Government there to do this.

But yeah, I'm in next door Portugal which has a similar history to Spain (though the Portuguese actually rebelled against and overthrew the Fascists - unlike the Spanish - which is probably why the mainstream Right in Portugal are nowhere as Fascist-inspired as in Spain) and the politicians in power seem to have chosen ultimate neutrality on this (well, at least this time around our provincial limp-dick politicians aren't straight up kissing American and German ass as they usually do) even though the party that recently got power (which is the straighforward Rightwing mainstream one and have a minority Government) earlier in the whole Gaza thing was quite pro-Israel, but seemed to have switched to a "we would rather not talk about it" posture since the coverage in the mainstream news here doesn't seem to try to hide anything when it comes to what's going on in Gaza (with things like showing lines of corpses after an Israeli bombing including clearly child-shapped ones and being pretty open about Israel killing journalists and medical personnel) and in a country were culturally people value empathy a lot, continue to side with Israel as people keep hearing about and at times seeing murdered chilren, journalists and medical personnel on TV would be a very bad strategy for a minority Government - even the local Far Right avoids mentioning that specific subject.