People make them in different ways. You can make several similar 88x31 pixel-art buttons in Photoshop or GIMP and then animate them (I believe both come with gif-making ability). For something more simple you could create a group of buttons to be animated here -> https://dabuttonfactory.com/ and then upload them to Gifmaker or EasyGif -> https://www.google.com/search?source=hp&ei=xa9oW5mzJeiQ0gLa57TIDQ&q=gifmaker&
@luficerslounge great question! I usually use a program called GraphicsGale, which is an older pixel graphics tool you can download for free: https://graphicsgale.com/us/ , but for the more complicated buttons, like NoticeMe and Alice Isn't Dead (where I need more color depth/losslessness in GIF and APNG exports) I use paint.net with the animated GIF/animated PNG plugnins: https://www.getpaint.net/
re: Gee whiz! 91 followers? Be careful Yudo, popularity comes with a curse.
oh wow im on here.. thank you so much. thats nice to see ;__;
Your button is really cool!