I certainly care about Syria and what has been done to people there.
One of the major differences between what's happening in Ukraine and what's happening in Syria is that Ukraine has a democratically elected government which opposes the Russian invasion. The Syrian government, on the other hand, invited the Russians in and their atrocities were carried out with its complicity.
"The Syrian civil war [...] is an ongoing multi-sided civil war in Syria fought between the Syrian Arab Republic led by Syrian president Bashar al-Assad (supported by domestic and foreign allies) and various domestic and foreign forces that oppose both the Syrian government and each other, in varying combinations."
en.wikipedia.org/wiki/Syrian_civil_war
Syria's head of state, Assad, already ran a harsh regime which prompted anti-government demonstrations in 2011 as part of the Arab Spring. Out of that grew a civil war which has been joined by a large number of outside groups, including Da'esh against Assad, and Russia for Assad at his request.
Syria is a hot mess. One wants to rush into the middle and shout "Stop this, the lot of you," but what would be the next step? Supposing one somehow militarily defeated... everybody... who would form the next government? How? This is the Afghanistan problem, of course. And even given 20 years of occupation and new government we saw what happened there.
Whereas in Ukraine, despite the "independent" regions and despite some of the many excuses Russia has been making for itself, Ukraine does have a functioning central government which does (appear to) oppose atrocities against its citizens. So there continues to be a “side” on which one can intervene which appears to be on the side of the lives of the country’s citizens. That government isn’t perfect (no side ever is, especially while there have been armed separatists and a foreign power controlling parts of the country), but it’s recognisable as a "good enough" side for many outsiders to support. This is being further underlined by what we're seeing of the way Russian soldiers have been treating people.
This is why Zelensky’s call for a foreign legion has had people in eg Nigeria turning up trying to volunteer. The Russian invasion of Ukraine is clear cut aggression by a foreign state, and the Russians’ treatment of civilians is looking increasingly like clear cut atrocities.
Kereti Usoroh, a Nigerian living in the capital, Abuja, said his motivations for volunteering had nothing to do with financial gain or the prospect of citizenship. "I already live a comfortable life. If I wanted to go to Europe, I'd do it through education, not war," the 29-year-old lawyer said. "This is about beating a bully - injustice for one is injustice for all."
www.bbc.com/news/world-africa-60712913