$ python
Python 3.10.2 (main, Jan 15 2022, 19:56:27) [GCC 11.1.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> a= "Betrag gr\xc3\xb6\xc3\x9fer als Betrag der Original-Transaktion"
>>> a
'Betrag gröÃ\x9fer als Betrag der Original-Transaktion'
>>> print(a)
Betrag gröÃ~ 

---------------

And above waits forever. Does not consume resources, but does not hear Ctrl-C. Ctrl-\ kills it.

The string above is just a byte string of the utf-8 representation, with forgotten "b" infront of it.

The ordinal range 0x80-0x9F is the C1 control code set [1]. Ordinal 0x9F is "Application Program Command" (APC). The command must be terminated by ordinal 0x9C, "String Terminator" (ST). For example, "\x9f Some Command \x9c". 

In Gnome Terminal, after executing print('\x9f'), an APC command without a terminator, typing Ctrl+L still works to clear the screen and get back to a prompt.

[1] https://en.wikipedia.org/wiki/C0_and_C1_control_codes#C1_controls

aha. ctrl-s also closes it.
seems kind-of ( ctrl-q - ctrl-s )
 https://en.wikipedia.org/wiki/Software_flow_control

thanks, closing this.

Note that the original issue seems to be that you had bytes but pasted it as a unicode string.  This works:

>>> b = b'Betrag gr\xc3\xb6\xc3\x9fer als Betrag der Original-Transaktion'
>>> s = b.decode('utf-8')
>>> print(s)
Betrag größer als Betrag der Original-Transaktion