Ukraine have bombed the Druzbha oil node in Russia completely cutting off Slovakia's access to oil & I think it's around 30% for Hungary.
A quick summary
Theres been a fair bit of backwards & forwards between SK & Ukraine over the pipeline for a while now, given Slovakia's location it depends entirely on this pipeline.
Ukraine wants the pipeline switched off to hurt Russia whilst without it Slovakia would be forced to import at huge expense.
Ukraine have a few times turned the pipeline off & in retaliation Slovakia have turned off the emergency electricity they supply to Ukraine when they need it, things have now escalated with Ukraine bombing the facility.
Croatia have offered to connect their pipeline to Slovakia but it's complicated & isn't something that can be done quickly.
The EU have asked Ukraine to repair the facility
There are now murmurings of the military getting involved by Slovakia & Hungary against Ukraine (more so from Budapest) but that is all I've seen so far.
This is an attack on two NATO members, if NATO was worth anything at all this probably would trigger at least some action from NATO alas were backing the 'good guy' in this civil war so both nations are left having to deal with Ukraine attempting to bully it's neighbours.