Hello,
If you install / uninstall rds service, you need to reboot your server because it is by design (like add feature in a windows client). Since you have changed your AD domain, if you are using Per User CAL, you should take care of your CAL because Per User CALs are stored in a domain user properties.
Your users will apply new CAL from your licensing server. (domain changed) If you don't have enough CALs, you may have trouble when using rds service. (until CAL which issued before expired) :
Per User RDS CALs show as expiring 60 days after they're issued. Shortly before their expiration date, when the user signs in, the date is extended another 60 days. If a user doesn't sign in before the expiration date, they drop off the list, but the next time they sign in they show up again with a new expiration date.
You can see this official link for details:
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