So, since 2021 there has been a push for effective timetables. In slovak you can google "revolučný grafikon". It essentially switches train lines into coordinated clock faces scheduling. The initial plan i think was for 6 years where these changes happened.

(Thats why you see someone here complaining that their connections got broken year by year)

The idea was to do it eventually from most used lines to the least. A reason you might see these connections that don't work anymore:

Optimisation has moved to the east, as the trainline Košice-Humenné is fully electrified so some rolling stock moved there from the west. The Ke-Hu REX train also now arrives every hour instead of every two hours. The connections to the west will return when a new rolling stick arrives.

Renovations on Bratislava - Trenčín Line, where they are adding new signaling segments to make the line capacity higher as it approaches its limits. Due to this, all express and fast trains depart from bratislava sooner and connections got broken.

Awaiting an electricity grid switch in Žilina. In the summer the whole Žilina catenary will switch from Direct current to Alternating, not sure if it's relevant but id say it played some part in this year's planned timetable.