I had this too but before my biometric request!
Oh gosh, and here I even gave you advice on it!!! Where is the facepalm emoji...?
Honestly, I'm hoping that this is just the final formality and essentially a request for an update, because I provided lots of information up front in the original application about my intent to return! We've also already gotten pre-arrival, so yeah, kinda weird, but I get the feeling this has become standard practice whenever the sponsor is living outside Canada. Not sure how much more to give them, considering I gave most of it in the original application, but I do now have one-way plane tickets for myself, husband and our dog, and, though it's not relevant to me as the sponsor per se, I also have my husband's uni acceptance and the deposit, which was paid on my credit card...
Did you hear anything after you submitted your proof? Updates in GCKey?