Description of problem: compiling latex doc with biber gets this error message Unescaped left brace in regex is deprecated here (and will be fatal in Perl 5.30), passed through in regex; marked by <-- HERE in m/}(\pM+\pL){ <-- HERE (?!\pL+\\)/ at /usr/share/perl5/Biber/LaTeX/Recode.pm line 297. system is up to date.
I think it should be fixed in a newer version of biber. But its not easy to bump :( Thanks for the report and I hope we can fix it eventually.
This is fixed for me in 2.11 which is in rawhide and will be in F29.