Hello @mara2021
It looks like you have a good plan in place for putting your 2019 Hybrid Servers in maintenance mode.
Almost identical to what I found, except some differences in the order. For more details you can refer to:
https://www.alitajran.com/put-exchange-server-in-maintenance-mode/
(Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.)
Also, if you want to run a script check out: Performing maintenance on DAG members
Regards
SF
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