I think the best way for you to access the logs in functional tests is not using the profiler, but to add the Monolog test handler in your test env:

# config/packages/test/monolog.yaml

monolog:
    handlers:
         [...]

        # Test handler allows to perform assertions on logs:
        test:
            type: test
            level: debug
            process_psr_3_messages: false
            channels: ["!event", "!doctrine"]

Declaring an alias to the service:

# config/packages/test/monolog.yaml

services:
    Monolog\Handler\TestHandler:
        public: true # to be accessible from tests
        alias: monolog.handler.test

you could easily access it in tests from the client container, and use its assertions methods.

hey there @ogizanagi! Thank you for your answer! I'll try this approach as soon as possible and I'll let you know :)

Hey, thanks for your report!
There has not been a lot of activity here for a while. Is this bug still relevant? Have you managed to find a workaround?

Hello? This issue is about to be closed if nobody replies.

Hey,

I didn't hear anything so I'm going to close it. Feel free to comment if this is still relevant, I can always reopen!

For people passing by, the solution provided by @ogizanagi works years later with Symfony 7.1. I successfully integrated it.
Many thanks!