Is the trolleybus catenary brand new on this street? Where does it lead to?

Yes, it's brand new, actually this was the first day of the operation here. From the place of the photo it only leads a few hundred metres further to the new loop located in the Kohoutova street. The trolleybuses are deviated here due to the construction works on the new segment of ring road in the area of Tomkovo náměstí.

Thanks for your answer. It is quite surprising to see new infrastructure being built for such diversions in 2022. I suppose that the main reason is because most trolleybuses aren't equipped with a diesel engine/battery... :P

Since it's a really long-term one and this new line was approved already in 2019, and also because of the reasons you have written, there weren't much possibilities how to keep trolleybus service on the lines 25/26 :D