Hello Giovanni
Port costs have indeed changed. Originally, they were calculated using the formula 1Gbps/bandwidth using a 16-bit number. This is called short mode. To accommodate the higher speeds available today and in the future, this has been modified to the use of a 32-bit number with the formula 20 Tbps / bandwidth. This is called long mode.
You can configure a switch to use either the short or long mode using the spanning-tree pathcost method
command. More info about this command can be found here:
https://content.cisco.com/chapter.sjs?uri=/searchable/chapter/content/en/us/td/docs/routers/nfvis/switch_command/b-nfvis-switch-command-reference/spanning_tree_commands.html.xml#wp4160553061
Keep in mind that most modern switches use the long path cost method by default.
I hope this has been helpful!
Laz