Hello,
It is quite hard to say what you are looking for, but you can always check official documentation:
https://docs.vmware.com/en/VMware-NSX-T-Data-Center/3.2.1/rn/vmware-nsxt-data-center-321-release-not...
From version 3.2.0 all the way up - there is always a known issues section.
For KB there is:
https://kb.vmware.com
Where you can find numerous articles regarding various things (NSX-T but also other products) related.
If you are looking for more proactive support I would advise you to use Skyline Advisor Pro if your internal policy allows it (you should have a running subscription plus know that Skyline sends your data elsewhere - not every company is ok with that). This way you can get basically everything I have written in a dashboard-packed-small-effort-proactive-solution way.
J.