Confirmed on IRC that this is a bug.
Relevant log¹ (edited for clarity):
<smls> Is it intended that LTM prefers \d and <[0..9]>
over <digit> and <:Number>, as a tie-breaker?
(re. RT #130612)
<TimToady> no, that wasn't intended
<jnthn> m: say '1' ~~ / \d | <digit> { say 'digit' }/
<camelia> rakudo-moar 760530: OUTPUT: «「1」»
<jnthn> m: say '1' ~~ / <digit> { say 'digit' } | \d /
<camelia rakudo-moar 760530: OUTPUT: «「1」»
<jnthn> Interesting
Though I can guess why
<jnthn> m: say '1' ~~ / \d | <:N> { say 'digit' }/
<camelia> rakudo-moar 760530: OUTPUT: «「1」»
<jnthn> m: say '1' ~~ /<:N> { say 'digit' } | \d/
<camelia> rakudo-moar 760530: OUTPUT: «「1」»
<jnthn> That one I don't understand
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[1] https://irclog.perlgeek.de/perl6/2017-09-11#i_15149008