Thanks for @DimmmCom to point out the config files. The problem was in the 443.conf file!
Whenever you have an additional domain configuration it creates a wrong config entry.
Example:
domain.com
www.domain.com
domain.ru
www.domain.ru
will result in a config like this:
listener SSL443 {
map domain.com domain.com
The additional RU domain is forgotten and therefor wont work and must be manually attached:
listener SSL443 {
map domain.com domain.com,domain.ru
@aaPanel_Jose can this issue be fixed? It still exists in the latest aapanel version 6.8.9