Hey @Henk S. so depending on your cluster (if you are Managed or SaaS) data is stored for certain periods of time. Problem cards will stay in the system for a full year. If you go into the system and select last 365 days in the time frame selector, you will see problems all the way from April of 2019 (assuming Dynatrace was running a year ago in your environment.) If a problem opens on a service and a month later that service is gone, that problem card will still remain in the system for up to a year. If you do a process rename and that process is still active, then the system will change the name of the process on all problem cards. So If you Change the name EasyTravel Service to VeryEasy Travel, and you look at the previous problem cards with that services having an issue, you will see it has been renamed.
If you want to read further as to how long data is retained for on multiple levels, check out this link: