Hello and welcome here to our community! 
- In my opinion, you’ll must contact support@vcvrack.com if nobody from here have the miracle solution!
Having tested (couple of minutes ago) from Bitwig Studio 5.1.9 + VCV Rack Pro (v2.6.6) either as VST3 and CLAP plugin format, running on Windows 10 platform. I confirm Spacebar key is filtered by VCV Rack 2, as long as it have the focus.
It looks any key is filtered, too, BTW you cannot benefit keyboard shortucts for any DAW as long as VCV Rack 2 plugin have the focus.
Please take a look about this topic: https://community.vcvrack.com/t/keyboard-stealing-spacebar-daw-transport-control/22051