Extended Events - is that a proof that the issue is not at the SQL Server side?

I have a problem with one PowerBI dashboard and I would like to ask for your advise if my logic is correct. We are migrating a few databases from one server (

) to the another one (

). At this moment we are on the testing phase. At one of the reporting servers (which is going to stay where it is for now, but it will be moved in some near feature) we have a PowerBI dashboard which pulls data from databases which we are moving. The refresh process at

was taking ~40s while at

it is ~2 minutes. The time difference for that particular issue is not a huge deal as it is refreshed in the background regularly so performance degradation will not be noticeable for the end users. But we are a little bit concern if that is an indication of the problem at the server level. So I need a way to check if the root cause of the performance degradation is at the SQL side or not. So at

(which is quite quiet as it is a test) I opened new Extended Events sessions that suppose to capture 'sql_batch_complited' events at user databases. Then I asked my colleague to trigger a refresh. Once it was completed I filtered results so timestamp was within ~3 minutes which were covering the report execution. Then I grouped by event name and summed duration. The result was about ~20s. My question is if that is 100% valid proof that the performance degradation is not caused by a new SQL engine, or new server being set up incorrectly. Or am I missing something?