https://lists.gnu.org/archive/html/bug-readline/2020-11/msg00010.html
says that bracketed mode is turned off if the terminal type is "dumb".
Setting TERM env var to dumb gives me a surprising behavior when I paste "1+1\n2+2" in Python REPL:
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$ TERM=dumb python3
Python 3.9.1 (default, Jan 20 2021, 00:00:00)
>>> ^J1+1^J2+2^J
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If I press ENTER, I get:
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>>> ^J1+1^J2+2^J
File "<stdin>", line 1
1+1
2+2
^
SyntaxError: multiple statements found while compiling a single statement
>>>
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Note: if I redirect Python output into a file ("python3 > output"), I get a different behavior since stdout is no longer a TTY.