Sorry, I meant how a space is made for the new tab to be placed in.
For some reason, Safari has the dragged tab take up the full space (the full tab bar), while CotEditor, a different app that uses native tabs, has the new tab take up the new amount of space it would take (half the tab bar).
Safari: https://cln.sh/DLmIi8
CotEditor: https://cln.sh/0Z2MTy