The following paragraph from this Le Monde article seems to explain their reasoning:

Zelensky's changing stance on these memory issues comes as the Kremlin's invasion of Ukraine in February 2022 has profoundly altered Ukrainians' relationship with their history. The authorities are now working to create a national pantheon to honor multiple figures of Ukrainian nationalism spanning centuries. Zelensky thus finds himself in a delicate position, caught between the risk of not meeting the demands of a narrative centered on resisting Moscow and the international repercussions of such memory policies.