Did you back up the encryption key from the old server and restore it on the new server?

Modify the ON to

On t.id = s.id
And t.startdate = s.startdate

then add a check for

When not matched by source
Then
Update
Set enddate =...

=Today.AddDays(0 - Today.Day)
=DateSerial(Year(Today), Month(Today), 1).AddDays(-1)

Alternative methods:
=Today.AddDays(1 - Today.Day).AddMonths(-1)  \\First of last month
=Today.AddDays(0 - Today.Day).AddMonths(0)  \\Last day of last month

=Today.AddDays(1 - Today.Day).AddMonths(-2)  \\First of...

How is the linked server configured 'to use a specified login'?
If you are adding a login named 'myuser' to MyLinkedServer - and then adding that as a user in...

I would recommend adjusting the configuration for the catalog first - instead of removing the logging.  Also - if you are running into space issues with SSISDB then you should...

Does the secondary have enough space available for the transaction log to grow?  I have run into issue where the secondary had 400GB drive - primary also had a 400GB...

Review the following articles:

https://www.brentozar.com/archive/2016/01/cheat-sheet-how-to-configure-tempdb-for-microsoft-sql-server/
https://www.sqlskills.com/blogs/paul/a-sql-server-dba-myth-a-day-1230-tempdb-should-always-have-one-data-file-per-processor-core/

As stated earlier - you need to create the login on each secondary with the same SID that was created on the primary.  When you create the user in the...