EDIT: This has been confirmed to be a bug upstream (https://gitlab.xfce.org/xfce/thunar/-/issues/808)
@twa022: The option can be found here
"Edit > Preferences... > Behavior > Tabs and Windows > Show full directory paths in tab titles"
I understand that this is 4.17.8 built from source; what I meant to say was this bug does not come up when building from source using the instructions given in Thunar's documentation on building (https://wiki.xfce.org/thunar/dev/build_and_run).
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