hello,
i have some suggestions which stem from my try to use this helm chart (with external db)
couple of problems with helm values:

domain:
  url: dbz.my.sv
database:
  enabled: false
  name: debezium
  host: postgresql.infra
  # port: 5432  <----- there is no port support here what if my db is on another port?
  auth:
    existingSecret: debezium-postgresql  #<------- if username and password is set this SHOULD be left empty but it's not possible 

and one more important thing i had to go through the code and read the database charts to see that i need to encode my username/password in secret to base64 before using, it's a good idea to append this to the description of the values in the docs.