The matter was reported by the portal lwowek24.pl:

Someone apparently got carried away in Lwówek Śląski (...); an unknown perpetrator probably threw eggs at the church of the Parish of the Assumption of the Blessed Virgin Mary. The shattered eggs beneath the church and stains on the building’s façade testify to the act.

Medium adds:

The church was built in 1209 and consecrated in 1241. Since then, it has been through a great deal, although little is known about acts of vandalism targeting it. The exception was the theft of the crozier from the nearby monument to Pope John Paul II.

Interestingly—as the Lwówek-based service pointed out—this was not an isolated case. Shattered eggs could be found in various parts of the city.

We remind vandals who are unable to channel their excess energy in a creative way that a serious act of vandalism is a crime punishable by between three months and as many as five years in prison.