Where has it gone? Bubble type notifs

[Android Central Question]

I really like the circle to oval message notification. As seen in films such as House of Cards. I do not care for the large rectangle white box that drops down for messg notifs. Both my s8 and s9 inotially had this look and type of circle expanding to an oval about a fifth down the screen. Then on both devices, this type went away and was replaced by the box type. Can anyone help/is anyone familiar? Thx.