You can create your own filters (pass it to the config part of the template object). Untested (I haven't written a filter in awhile) but if it's not right, it's close-

use URI::Escape ();

FILTERS => {
            uri_unescape => sub {
                URI::Escape::uri_unescape(@_);
            },
},
----
Then in the template: [% my_uri_string | uri_unescape %].
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It seems a bit strange to have an unescaped URI given to the template though. Probably there is something in the backend which is not being handled as well as it could be.