This is an addition to the excellent answer by David Hammen in order to give more historic and local context.
During the time of the USSR, Russian Orthodox Church was essentially under a complete control of the state. Specifically, priests were reporting to KGB and often were KGB officers.
The arrangement was beneficial for the regime. On the one hand, they were letting a bit of steam go off as there are always some religious people even in a formally atheist state. On the other hand, the priests were providing an extremely valuable intelligence on the population, especially on the groups which were known for being disloyal.
If you look deeper into the history, you can see that strong ties between the Moscovian government and the Russian Orthodox Church can be traced back at least to the times of Ivan the Terrible, who was controlling the church with an iron grip.
With the fall of the USSR KGB got split and rebranded as FSB in Russia / SBU in Ukraine. The Russian Orthodox Church meanwhile remained tightly connected to the former KGB. Not everyone was happy with this. Simplifying a bit, this has resulted in a split within the church. Now there are multiple Orthodox Churches in Ukraine. For example, there is an Orthodox Church of Ukraine, which is a result of unification of several orthodox churches in Ukraine.
The church which got a "special attention" from SBU these days is the Ukrainian Orthodox Church of Moscow Partiarchate. For a long time it has enjoyed pretty much an immunity and nobody dared to touch it. In the meantime, there were plenty of publicly known cases anti-Ukrainian activities ranging from not performing funerals for the fallen Ukrainian soldiers and telling the congregation that Ukraine must fall and be re-unified with "mother Russia" to cases where in the occupied territories the priests were helping the invaders to identify people who should be captured and houses which should be robbed first and gathering intel on Ukrainian forces for Russia.
It probably also did not help that during one of the raids a priest was caught in bed with a boy. This was hardly a surprise as this kind of behaviour is an open secret. For example, a famous Russian journalist Aleksandr Nevzorov (who used to study in Moscow Theological Academy) was talking about it for years. It is only now, however, that someone was publicly caught in the act.
So in Ukraine these raids by SBU are not seen as attacks on Christianity.
In fact, people are very supportive of this. They even jokingly say that SBU ("СБУ" - "Служба Безбеки України" - "Ukraine's Security Service") is in fact "Служба Божа України" (Ukraine's God's/Godly Service).
Many people are very happy indeed that this is happening, although they express unhappiness that it took decades for SBU to begin looking at this problem.