Have you tried the suggested workarounds in the other thread like the Launch and DTM Switch?
Else, you might also use the Requestly extension to rewrite URL based on rules like "URL contains".
The // prefix is a relic from times when there were still non-https websites around and you wanted to load the script implicitly with the same protocol.
Nowadays I would always explicitly do https tbh. Maybe check with your devs to change it on their website as well.
But bottom line, it should ideally be handled properly by the extension.
You may post this as product idea as well
Cheers from Switzerland!