did you try the index and the insert into a temp table as I suggested?
If so what were the results

look at https://support.microsoft.com/en-us/help/918992/how-to-transfer-logins-and-passwords-between-instances-of-sql-server
contains code for both functions.

you may also wish to look at https://dbatools.io/ for other tools to do this (and a lot more)

missing index as per explain plan might help a bit there.

you could try changing the index to IX_PROPERTY__SOURCE_ID be as follows

create nonclustered index IX_PROPERTY__SOURCE_ID...

SSAS tabular only works with Windows authentication. So if the server is indeed in Tabular mode you need to try it that way.

either repeat or use one of the following 2 options.

select *
from (select t1.field1
    , t1.field2
    , (select top 1 otherfield
    ...

hum.... may have misread it initially. @SQL_CODE is what contains all the calls to dbo.elast.... bad design on how it was implemented.

so back to those functions. Not sure which...

@alexandermkd 
the code for proc TARIFF_SIM_MATRIX_3M does not match that of the code being executed as per the explain plans you supplied.

just...

@jeff - the OP has already tried the some trace flags and also had the legacy configuration turned on .
ALTER DATABASE SCOPED CONFIGURATION SET LEGACY_CARDINALITY_ESTIMATION = ON is the...

you can still do it although manually.

look at table XVBS_LOG_3M and identify the offer_id that took the longest (you need to compare each record with the previous one...