checking if it is a holiday based on date using holidays library -python

I have a dataset from the last 3 years, I would like to add a new column based on holidays. when I try this :

import holidays
de_holidays = holidays.DE()
for date, name in sorted(holidays.DE(years=2021).items()):
   print(date, name)

I get the result

2021-01-01 Neujahr
2021-04-02 Karfreitag
2021-04-05 Ostermontag
2021-05-01 Erster Mai
2021-05-13 Christi Himmelfahrt
2021-05-24 Pfingstmontag
2021-10-03 Tag der Deutschen Einheit
2021-12-25 Erster Weihnachtstag
2021-12-26 Zweiter Weihnachtstag

now I wanted to create a new column in my existing dataset with true/false in case of holiday. I tried to use the below code snippet.

My Date column looks something like this: Dtype is datetime64[ns]
2021-07-22  
2021-07-21  
2021-07-20  
2021-07-19  

#I used the code 
import holidays
de_holidays = holidays.DE()
df['Holiday'] = df['Date'].isin(de_holidays)
rslt_df

rslt_df.loc[rslt_df['Date'] == '2021-05-13'] 

The result I was expecting is True as 13th may was a holiday but I realized this code is giving all the false values. can anyone help?

edit

12390   2021-07-22
12380   2021-07-21
12370   2021-07-20
12360   2021-07-19
12350   2021-07-18
           ...    
40      2018-03-05
30      2018-03-04
20      2018-03-03
10      2018-03-02
0       2018-03-01
Name: Date, Length: 1240, dtype: datetime64[ns]

now when I use

df['Holiday'] = df['Date'].isin(holidays.DE(years=2021))

I get the correct True/False values but as soon as I remove years tab then I get all the false value

df['Holiday'] = df['Date'].isin(holidays.DE())

Answer

This works well to get Boolean Value

from datetime import date
import holidays
de_holidays = holidays.DE()
#date(2021-07-22) in de_holidays

rslt_df['Holiday'] = rslt_df['Date'].isin(holidays.DE(years=[2018,2019,2020,2021]))
rslt_df