I also posted into Engineer class forum about that, still dunno if what’s happening recently to the master trait Grenadier is bugged or working as intendend.
Seeing that there still none was sure about it, in the doubt i’ll post here too looking for a clarification:
https://forum-en.gw2archive.eu/forum/professions/engineer/Experiencing-Grenadier-trait-stopping-Grenades-from-arching-anymore/first#post363658