This does not sound reasonable to me so I propose declining this.
In general, new systems have improvements / advantages and regressions / disadvantages.
Full functionality was never a goal when replacing systems, rather better functionality and improvements in many areas.
I think that's the case when I see acceptance among development teams and the generally higher number of active users per month than in Bugzilla.
I feel Andre covers my view of this perfectly really.
Also a general bug which can be categorised as basically "everything is stopping this happening" is not really helpful especially when the information given is so generalised as well.