Percona DB psmdb-db charts

I have created MongoDB shared cluster.
I want user credential like (example)
"
users:
MONGODB_BACKUP_USER: backup
MONGODB_BACKUP_PASSWORD: backup@123456
"
I want to use special character in MONGODB_BACKUP_PASSWORD.
how can I do without encoding ?
One way which worked to use (%40 in place of ‘@’)
"
users:
MONGODB_BACKUP_USER: backup
MONGODB_BACKUP_PASSWORD: backup%40123456
"
but I don’t want to encode because it cause crashloopbackoff of the pods , how can I do ?
if I use directly or with quote (‘backup@123456’) pods restarts multiple time.

for reference : https://github.com/percona/percona-helm-charts/blob/main/charts/psmdb-db/values.yaml
line no- 469