Note: T5 Version 1.1 was only pre-trained on C4 excluding any supervised
training. Therefore, this model has to be fine-tuned before it is usable on a downstream task, unlike the original T5
model. Since t5v1.1 was pre-trained unsupervisedly, there's no real advantage to using a task prefix during single-task
fine-tuning. If you are doing multi-task fine-tuning, you should use a prefix.
Google has released the following variants:

google/t5-v1_1-small

google/t5-v1_1-base

google/t5-v1_1-large