The game's product page confirmed the shut down: "Multiplayer and all online features for this product will be terminated and will no longer be available on 07/25/19. As you have to be online to play this title, this game will not be playable starting 07/25/19."
PSVR games that can only be played online is an issue that we've raised before with titles like Megalith and Firewall Zero Hour, and it looks like StarBlood Arena is feeling the full force of a lack of any player base. The game was even handed out as a PlayStation Plus extra in December of 2017, but that doesn't seem to have resulted in larger player counts.
We can't say we'll miss it, but were you hoping to check out StarBlood Arena? Try to fit it in before July in the comments below.