My 4-m.o baby still doesn't recognize plush toys even though they're very colorful. Is it too early for them to recognize them?

Your baby has just started to distinguish subtle shades of colours. Red and blue tend to interest infants more at this age. At this age, your baby should be able to track the movement of the toy with her eyes and grasp or reach out for the toy. Try Lamaze toys. They're targeted at infants and come in bright, bold colours with different sounds, textures and shapes. https://www.healthychildren.org/English/ages-stages/baby/Pages/Your-Babys-Vision-4-to-7-Months.aspx