Launching a second Camoufox instance breaks the first one (instances interfere with each other)

[Bog555]

Description
When I launch the first Camoufox instance, everything works fine:

the page loads correctly
my code starts working
I can click buttons
But as soon as I start a second Camoufox instance, both the first and the second stop working properly.
It looks like they interfere with each other.

Previously this worked without any problems — I was able to run up to 10 simultaneous Camoufox instances at the same time.
Now even running 2 instances causes failures. I don't know what has changed.

Steps to Reproduce
Launch the first instance with a dedicated --user-data-dir and --remote-debugging-port.
→ It loads correctly and works as expected.
Launch the second instance with a different --user-data-dir and port.
→ Immediately, both the first and second instances freeze or stop functioning.
Expected Behavior
Multiple Camoufox instances should work independently, without interfering with each other.
At least 10 simultaneous instances should be possible (as before).
Actual Behavior
The first instance works fine until the second is launched.
As soon as the second starts, both break.
Environment
Setup: Each instance is launched with its own unique --user-data-dir and --remote-debugging-port.
Question
Could something have changed in recent Camoufox updates that prevents multiple instances from running in parallel?
What should I check to restore multi-instance support?

[reddere]

"Previously this worked without any problems — I was able to run up to 10 simultaneous Camoufox instances at the same time."

previously, when it used to work, what version did you have? @Bog555