Consider:
```
from typing import Protocol

class P(Protocol):
    ...

class C(P):
    def __init__(self):
        super().__init__()

C()
```
This code passes without error on 3.9.6.

With 3.9.7, we get:
```
Traceback (most recent call last):
  File "/Users/shantanu/dev/test.py", line 10, in <module>
    C()
  File "/Users/shantanu/dev/test.py", line 8, in __init__
    super().__init__()
  File "/Users/shantanu/.pyenv/versions/3.9.7/lib/python3.9/typing.py", line 1083, in _no_init
    raise TypeError('Protocols cannot be instantiated')
TypeError: Protocols cannot be instantiated
```

I bisected this to:

bpo-44806: Fix __init__ in subclasses of protocols (GH-27545) (GH-27559)

Note there is also an interaction with the later commit:

bpo-45081: Fix __init__ method generation when inheriting from Protocol (GH-28121) (GH-28132)

This later commit actually causes a RecursionError:
```
  File "/Users/shantanu/dev/cpython/Lib/typing.py", line 1103, in _no_init_or_replace_init
    cls.__init__(self, *args, **kwargs)
  File "/Users/shantanu/dev/test.py", line 8, in __init__
    super().__init__()
  File "/Users/shantanu/dev/cpython/Lib/typing.py", line 1103, in _no_init_or_replace_init
    cls.__init__(self, *args, **kwargs)
  File "/Users/shantanu/dev/test.py", line 8, in __init__
    super().__init__()
```

Originally reported by @tyralla on Gitter.

Possibly related to issue 45081, which ended up not having anything to do with dataclasses (despite the title).

Can you check if that fix solves your problem?

As I mentioned in the post, bpo-45081 actually makes this issue worse, since we get a RecursionError.

I think `TypeError: Protocols cannot be instantiated` is probably okay behaviour (as opposed to RecursionError), more just unfortunate that it seems to be an unanticipated breaking change.

Sorry if my message was confusing. Hopefully the following makes things clear:

3.9.6: snippet runs without error

3.9.7, with bpo-44806: (a probably reasonable) TypeError, but a breaking change

main, with bpo-45081: RecursionError

Sorry I didn't notice your reference to issue 45081.

New changeset c11956a8bddd75f02ccc7b4da7e4d8123e1f3c5f by Yurii Karabas in branch 'main':
bpo-45121: Fix RecursionError when calling Protocol.__init__ from a subclass' __init__ (GH-28206)
https://github.com/python/cpython/commit/c11956a8bddd75f02ccc7b4da7e4d8123e1f3c5f

New changeset 99506dcbbe9fb56ceabe55f0a4333e5981b72095 by Ken Jin in branch '3.9':
[3.9] bpo-45121: Fix RecursionError when calling Protocol.__init__ from a subclass' __init__ (GH-28206) (GH-28233)
https://github.com/python/cpython/commit/99506dcbbe9fb56ceabe55f0a4333e5981b72095

New changeset c081649e6df55203178a44d16bc4c96f9fa2c6a4 by Miss Islington (bot) in branch '3.10':
bpo-45121: Fix RecursionError when calling Protocol.__init__ from a subclass' __init__ (GH-28206) (GH-28232)
https://github.com/python/cpython/commit/c081649e6df55203178a44d16bc4c96f9fa2c6a4

Pablo, marking as release blocker. PR GH-28232 is merged to 3.10. It should be cherry-picked for 3.10.0 inclusion.

> Pablo, marking as release blocker. PR GH-28232 is merged to 3.10. It should be cherry-picked for 3.10.0 inclusion.

Done!

New changeset db762a9b21a8af6f2ee94a6e49144dd1a1a62333 by Pablo Galindo (Miss Islington (bot)) in branch '3.10':
bpo-45121: Fix RecursionError when calling Protocol.__init__ from a subclass' __init__ (GH-28206) (GH-28232)
https://github.com/python/cpython/commit/db762a9b21a8af6f2ee94a6e49144dd1a1a62333