Maybe this was mentioned earlier: vmassol reported the issue in the URLRewriteFilter tracker. As far as I understand from paultuckey's recent comments (creator of the lib), a fix is doable, just not implemented yet.

Vincent Massol you suggested to report the issue directly to Tomcat's Bugzilla, which seems like a good idea indeed. Would something like the report below describe the improvement request accurately?

Title: Add ability to rewrite outbound URLs

Description: The recently introduced RewriteValve allows to rewrite inbound URLs. This ticket proposes to implement in addition the ability to rewrite outbound URLs. This would allow to support the same types of rules as URLRewriteFilter was supporting up to Tomcat 9 and does not anymore due to the early mapping now done very early in Coyote which prevents the filter to be applied.

The only issue I could find currently in Tomcat's bug tracker about URL rewriting is an old one covering a distinct need: RewriteValve: Implement additional RewriteRule directive capabilities.