then it can be different execution plans, if there are no locks

are the...

=IIF(Fields!NextService.Value = "Substance Abuse",Fields!DaysToNextService.Value,0)

?

PS usage of AVG in the original expression is not clear

...
where n>10

?

ELSE '0' END

it's better to post questions in English to avoid issues with translation

regarding your case:    it's better to use BCP command because you can specify field delimiters (-t",") and get...

Visual check of all 6 datasets went well ?

Did you check report itself (view code) and line 71 ?   Is there anything suspiciuos?

I would get list containing  current connected, extracted from default  trace  and copy them to the new server enabled,  the rest I would copy disabled .

When the new server is...

try this one:

https://www.richardswinbank.net/admin/extract_linked_server_passwords

try this one:

with data as 
(
select 
row_number() over (partition by partnumber order by id desc) [n]
,id, Nome_posto, data, lote, serialnumber, partnumber,versao,indexnumber,semana,qrgerado,operador,snpn
from etiquetasklc.dbo.etiquetas2018

)

/* 
insert
into etiquetasklc.dbo.etiquetas (id,Nome_posto, data, lote,...

it can be due to the misconfiguration of SSRS

first ideas:

1. it tries connects to the wrong SQL instance
2. it's not configured...

I saw such issues in the past when SSMS had issues reading BAK files created with option "copy_only".

Try to run the following commands from query window:

restore headeronly...

Typo?

"Certainly the more debt that piles up, the mode (more?) difficult it can be to change code. "

Jeff,  function dbo.fnTally  is a custom one, I suppose.

Could you provide a link to its definition?

One DBA can change password for such sole login and no one will connect.

security best practices (minimum) :   each dba has its own login,  all logins are in AD group, ...

https://docs.microsoft.com/en-us/sql/relational-databases/databases/database-snapshots-sql-server#LimitsOnDbSS