widget is being recognized as a frame when using place on a different widget python 3 tkinter

Do not mix geometry management algorithms within a container. You are using pack for start_btn and place for about_btn both in the home_frame container. Pick one - ideally either grid or pack. Place is not usually sensible.

For example, to pack your buttons on a row at the top and right:

self.home_frame.pack(side=tk.TOP, fill=tk.BOTH, expand=True)self.about_btn.pack(side=tk.RIGHT, anchor=tk.NE)self.start_btn.pack(side=tk.RIGHT, anchor=tk.NE)

Using place instead:

self.home_frame.place(relwidth=1.0, relheight=1.0)self.start_btn.place(relx=0.5, rely=0, relwidth=0.25)self.about_btn.place(relx=0.75, rely=0, relwidth=0.25)

Frankly, learn to use grid. It will be worth it. Here is a reworked version that illustrates all three geometry managers for two buttons.

import tkinter as tkclass App():    def __init__(self, parent):        self.app = parent        self.app.geometry("300x300")        self.app.title("test application")        f1 = tk.Frame(self.app, relief=tk.GROOVE, borderwidth=2)        b1a = tk.Button(f1, text="Place A")        b1b = tk.Button(f1, text="Place B")        b1a.place(relx=0.5, rely=0, relwidth=0.25)        b1b.place(relx=0.75, rely=0, relwidth=0.25)        f2 = tk.Frame(self.app, relief=tk.GROOVE, borderwidth=2)        b2a = tk.Button(f2, text="Two A")        b2b = tk.Button(f2, text="Two B")        b2b.pack(side=tk.RIGHT, anchor=tk.NE)        b2a.pack(side=tk.RIGHT, anchor=tk.NE)        f3 = tk.Frame(self.app, relief=tk.GROOVE, borderwidth=2)        b3a = tk.Button(f3, text="Grid A")        b3b = tk.Button(f3, text="Grid B")        b3a.grid(row=0, column=0, sticky=tk.NE)        b3b.grid(row=0, column=1, sticky=tk.NE)        f3.grid_rowconfigure(0, weight=1)        f3.grid_columnconfigure(0, weight=1)        f1.grid(row=0, column=0, sticky=tk.NSEW)        f2.grid(row=1, column=0, sticky=tk.NSEW)        f3.grid(row=2, column=0, sticky=tk.NSEW)        for row in range(0,3):            parent.grid_rowconfigure(row, weight=1)        parent.grid_columnconfigure(0, weight=1)if __name__ == "__main__":    root = tk.Tk()    app = App(root)    #app1.resizable(False, False)    root.mainloop()