Much appreciated...I had the same question, but didn't get a clear answer. I'll try and be neutral, but yhis is what I have gathered.
The TPLF is the former ruling party of Ethiopia. They have since been replaced by Abiy Ahmed's Prosperity Party in 2018 after unprecedented protests from the Oromos. They no longer lead the 'coalition' of parties that headed the previous government, but they are still the legal representative of their regional Tigray state. The TPLF has been passive aggressively player hating and feels victimized under Abiy's new government as he has been actively trying consolidate and centralize power. This undermines Ethiopia's current system governance (ethnic federalism) where every major ethnic group gets to rule their own regions to some extent. Historically though, most regions were headed by devolved puppet governments. During their reign they have brutally suppressed various other ethnic groups, among which Somalis.
This past summer the regional election(s?) were due and the central government told the TPLF to suspend elections like many other places in the world due to the pandemic. The TPLF refused and held elections anyway where they won with an alleged 98% of the votes. Abiy in turn cut funding from the region for undermining the central government's authority. The TPLF responded by refusing to submit taxes. The Tigray region is disproportionately wealthy, in part due to looting the government for 3 decades. The central government at some point also tried to replace the leadership of the Northern Command (the national military staged in the Tigray region) because he feared that it might be loyal to the regional TPLF instead of the central government. They sent new leadership only to be sent right back.
I'm not a 100% sure if the aforementioned events happened chronologically. But at some point Abiy moved other parts of the military towards Tigray and either elements loyal to the central government attacked the TPLF, or the TPLF prematurely struck to loot the military base for weapons. I think it has since been clarified that it was the Tigrayans that attaked the military, but it is unclear whether or not it was provoked.
Now the Tigray region is being invaded by the Ethiopian army along side Amhara militias and with aid from the Eritreans who are bitter foes of the TPLF.
For the most part Habesha on Habesha violence. As far as I'm aware, Somalis have no active interest in rooting for either parties.