We have a discussion in our group. Our cleric was being blessed (the spell) by the paladin and shortly after polymorphed (also the spell) into a T-rex by the wizard. Is the T-rex still blessed?Or is the T-rex a different entity, and therefor not blessed?
Magical effects continue unless there's a reason for them to stop. For bless to end, it needs to expire, the caster lose concentration, or be dispelled. Certain other abilities can end magical effects, but merely having a different magical effect doesn't stop the previous ones.
I could see the argument for true polymorph cancelling bless if you turned the creature into an object (which would no longer be a valid target for bless).