Clarification on InterceptHandler behavior

[BayerSe]

Hello,

I've got another question where I'd need some help. In particular, I'd like to understand the following behavior. If I open a fresh console and print all loggers

import logging
for logger in [logging.getLogger(name) for name in logging.root.manager.loggerDict]:
    print(logger)

I get the following output:

<Logger _plotly_utils.optional_imports (WARNING)>
<Logger _plotly_utils (WARNING)>
<Logger _shaded_thriftpy.server (DEBUG)>
<Logger _shaded_thriftpy (DEBUG)>
<Logger concurrent.futures (WARNING)>
<Logger concurrent (WARNING)>
<Logger asyncio (WARNING)>

... a mixture of different loggers and log levels.

If I now apply the InterceptHandler and reprint the loggers:

import inspect
import logging

from loguru import logger


class InterceptHandler(logging.Handler):
    def emit(self, record: logging.LogRecord) -> None:
        # Get corresponding Loguru level if it exists.
        level: str | int
        try:
            level = logger.level(record.levelname).name
        except ValueError:
            level = record.levelno

        # Find caller from where originated the logged message.
        frame, depth = inspect.currentframe(), 0
        while frame and (depth == 0 or frame.f_code.co_filename == logging.__file__):
            frame = frame.f_back
            depth += 1

        logger.opt(depth=depth, exception=record.exc_info).log(
            level, record.getMessage()
        )


logging.basicConfig(handlers=[InterceptHandler()], level=0, force=True)

for logger in [logging.getLogger(name) for name in logging.root.manager.loggerDict]:
    print(logger)

I get

<Logger _plotly_utils.optional_imports (NOTSET)>
<Logger _plotly_utils (NOTSET)>
<Logger _shaded_thriftpy.server (DEBUG)>
<Logger _shaded_thriftpy (DEBUG)>
<Logger concurrent.futures (NOTSET)>
<Logger concurrent (NOTSET)>
<Logger asyncio (NOTSET)>

I guess that the NOTSET comes from level=0 in the basicConfig call? If that is the case, why are _shaded_thriftpy.server and _shaded_thriftpy still at DEBUG?

This happens for other libraries too, not only the internal stuff: some stay at their original level, some switch to NOTSET.