Smooth and soothing in manner or quality. (Merriam – Webster)
Exhibiting no personal concern or embarrassment: Unperturbed. (Merriam – Webster)
Not irritating, stimulating, or invigorating: Soothing. (Merriam – Webster)
Pleasantly gentle or agreeable: (Dictionary.com)
Soothing or balmy, as air: (Dictionary.com)
Not having a strong taste or character or not showing any interest or energy. (Cambridge Dictionary)
If you describe someone or something as bland, you mean that they are rather dull and unexciting. (Collins Dictionary)
Bland Diet that is soothing to the guts.
Ten Incredibly Bland Movies For Bland People.