Hello,
This should work (tested on regexr.com) :
/features:.*:start/[/m] and if you need to target also features:start [m]/features:.*:*start/
Text tested :
features:featureA:start
features:featureB:start
features:featureC:foo
features:featureD:start
features:start
features:featureA:start
features:featureA:PageCDE
As said in the
config startpage doc, it should be a valid pagename and never contain a namespace, so you have to avoid
features:featureA:start:PageCDE