Hi, Homebrew developer here, we're seeing this with macOS 11.1 and I think it's not a python issue but an Apple's Tcl/Tk issue. The backtrace I have is:

0   libsystem_kernel.dylib        	0x00007fff2031f462 __pthread_kill + 10
1   libsystem_pthread.dylib       	0x00007fff2034d610 pthread_kill + 263
2   libsystem_c.dylib             	0x00007fff202a0720 abort + 120
3   Tcl                           	0x00007fff6fe1eb55 Tcl_PanicVA + 398
4   Tcl                           	0x00007fff6fe1ebd5 Tcl_Panic + 128
5   Tk                            	0x00007fff6ff1ead5 TkpInit + 385
6   Tk                            	0x00007fff6fe9e788 0x7fff6fe6d000 + 202632
7   _tkinter.cpython-39-darwin.so 	0x0000000102d2d701 Tcl_AppInit + 84
8   _tkinter.cpython-39-darwin.so 	0x0000000102d289fa _tkinter_create + 975
9   org.python.python             	0x00000001027251bb cfunction_vectorcall_FASTCALL + 203
10  org.python.python             	0x000000010279cff3 call_function + 403
11  org.python.python             	0x000000010279a184 _PyEval_EvalFrameDefault + 27452
12  org.python.python             	0x000000010279db3b _PyEval_EvalCode + 1998
13  org.python.python             	0x00000001026f55d8 _PyFunction_Vectorcall + 248
14  org.python.python             	0x00000001026f4e67 _PyObject_FastCallDictTstate + 212
15  org.python.python             	0x00000001026f5891 _PyObject_Call_Prepend + 139
16  org.python.python             	0x000000010273de96 slot_tp_init + 87
17  org.python.python             	0x00000001027376f7 type_call + 150
18  org.python.python             	0x00000001026f4fa3 _PyObject_MakeTpCall + 266
19  org.python.python             	0x000000010279d027 call_function + 455
20  org.python.python             	0x000000010279a184 _PyEval_EvalFrameDefault + 27452
21  org.python.python             	0x000000010279db3b _PyEval_EvalCode + 1998
22  org.python.python             	0x000000010279356d PyEval_EvalCode + 79
23  org.python.python             	0x00000001027ce5b5 run_eval_code_obj + 110
24  org.python.python             	0x00000001027cd9ad run_mod + 103
25  org.python.python             	0x00000001027cc9dc PyRun_StringFlags + 182
26  org.python.python             	0x00000001027cc8e9 PyRun_SimpleStringFlags + 69
27  org.python.python             	0x00000001027e3802 Py_RunMain + 425
28  org.python.python             	0x00000001027e40c1 pymain_main + 306
29  org.python.python             	0x00000001027e410f Py_BytesMain + 42

This seems confirmed by the fact that I can reproduce with Apple's own python:

$ /usr/bin/python3 
Python 3.8.2 (default, Nov  4 2020, 21:23:28) 
[Clang 12.0.0 (clang-1200.0.32.28)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import tkinter
>>> root = tkinter.Tk()
macOS 11 or later required !
zsh: abort      /usr/bin/python3

I will file a bug report with Apple.