I just did a few thoughts.
GC is by law allways binded to work, meaning if someone loses job, visa is invalid. Even if guy does not have visa binded to firma or even if there is no:
erlischt mit Beendigungder Tätigkeit
in pass. Visa is invalid without job because law says so.

BUT AFTER 1.1.???
After 1.1. GC law is invalid so if one loses job situation is different.

If he has visa binded to firma or
erlischt ...
in visa then his visa is invalid without job.
Same as before.
BUT ...
if he has visa that says only:
Erteilt nach § 1 IT-AV. Nur gültig für die Beschäftigung als IT-Fachkraft, sofern gültige Arbeitserlaubnis vorliegt.
THEN VISA SHOULD BE VALID EVEN IF ONE LOSES JOB.
It is so because after 1.1. GC is same as every other visa and other visas are binded to firma or completely free.
So when GC is not binded to firma then it is not binded to Tätigkeit also, completely free, meaning valid even without job.
So if someone loses job after 1.1. situation should be better than before 1.1. if it is not binded to firma.
Actually even if it is binded to firma GC could be regarded as free becuse according to law GC is allways permit for whole IT bransche.

SO ACTUALLY ALL GC SHOULD BE LITLE BIT BETTER AFTER 1.1. because they SHOULD BE VALID EVEN IF ONE LOSES JOB.

Bei mir steht "Nur gültig für eine Tätigkeit als IT-Fachkraft. Studium nicht gestattet. Erwerbstätigkeit nicht gestattet."
So, du hattest Recht. Egal ob das wir haben oder nicht haben arbeit, das Visum ist gültig.
Nur ist sehr wichtig das man muss arbeit haben wann NE versuchen wird....

You are not allowed to study.
WHAT IDIOTS.
FROM YOUR TAXES THEY PAY UNIS AND THEY WOULD NOT LET YOU STUDY.
SO SOMEBODY FROM SOMEWHERE THAT NEVER PAID ANY TAXES CAN STUDY IN DE BUT YOU NOT.
UNBELIVABLE!!!!!

And what if I had something like that on my first Visum ("gem. § 5 NR. 2 bla-bla" ), but they left it out when I received my new Visum (I had to switch passports in the meantime)?
I can just wonder about the fate's irony? ;)

Depends on what they wrote in new pass.
It could be better but also worse than before.
I know one guy that was so lucky to get visa without this IT.thing in it and even selbstständige tätigkeit was allowed.
What is even better his wife got same unbeschränkte visa (she was not GC and did not work).

So actually with that visa he could be 5 years arbeitslos in De but it would still be valid.

I don't have second page on my new visa. Does that mean I can open company etc.

sun

Probably