the connection string is not written correctly. Reference document for correct format: https://docs.mongodb.com/manu.
for example:

mongodb://db1.example.net:27017,db2.example.net:2500/?replicaSet=test

change to the following configuration

-sharp mongodb
spring.data.mongodb.host=your-mongodb-url
spring.data.mongodb.port=your-mongodb-port
spring.data.mongodb.username=your-mongodb-username
spring.data.mongodb.password=your-mongodb-password
spring.data.mongodb.database=your-mongodb-database
spring.data.mongodb.authentication-database=admin