[DRG]

SPECULATION there a plenty of other tanks available that have been in service for some time that crews are fully trained on. The T-14 is still undergoing field trials (IIRC).

Yes, this would be a good place to do "field trials" but OTOH you wouldn't really want to take the chance that one, or more might be destroyed or break down and be captured. It would be quite a propaganda coup for Ukraine to show a destroyed one to the world

Plus I suspect ( more speculation) that this "'special military operation' " was expected to be over quickly and bringing them into it was thought unnecessary.