Question about text2img pretrained weight

[HyoungwonCho]

Hello, I would like to inquire about the text2img pretrained weight uploaded on February 21, 2022, and the text2img-large pretrained weight uploaded on April 1, 2022, by leaving this issue.

Were these two weights trained by mixing in empty prompts instead of text prompts during the training process, as introduced in classifier-free guidance, or were they purely trained with text-image pairs only?