for the same route destination we have the same AS_PATH (2 hops).
So, we’re setting a lower MED value to prefer the left transit instead the right one.
But, seems is not taking affect as the router is prefering the right route that we set with higher MED.
There is not any differente setting a lower o highest MED value. Nothing change.
If you’re trying to influence traffic out of an AS (which is what you appear to be doing) then I would start with marking localpref higher on the route you want to be preferred. localpref, unlike weight will be learned by every router in the AS (unlike weight)
MED only applies when left most AS is common. It’s primarily used to influence which link a neighbor uses when there are redundantly uplinks.
To influence a remote network you would need to agree on them building filters that change local preference using something that you can attach to a route which is inert everywhere else, precisely what BGP communities were designed for…