AWS SES API strange test and save behavior

Your software
My Mautic version is: 4.4.5
My PHP version is: php74
My Database type and version is: 10.4.27-MariaDB

Your problem
My problem is:
Go to |config|email settings|Mail Send Settings:

Service to send mail through: Amazon SES-API
Username for the selected mail service: Enter the AWS SES Access key ID (e.g. AKIA***)
Password for the selected mail service : Enter the Secret access key
Click test connection: result is success
Now click save:
result:the field “Username for the selected mail service” is replaced by the AWS SES Username ( and the password is geplaced
Expected behavior: The filled out user is shown and not replaced and password is not replaced. Why
click test connection again
result: error about creditials

In other cases when opening the screen for the first time a different user is shown (my name).

This situation makes it hard to find causes of emails not being send.

Possible causes I can think of:
The old SES SMTP option has user and password stored and is in the way. Could not find that in local.php though.
The monitored Inbox settings is currently not working since MS stopped IMAP support
Testen in Chrome

These errors are showing in the log:

Steps I have tried to fix the problem: