I just tried changing my ear tips. Went from the medium sized ones, which were by far the most comfortable, to the large ones, which I literally had to jam into the ear canals, to the point where they're so tight half the time when I take the headphones out the ear tips actually fold out inverted.
The ANC did get ever so slightly better I guess but not enough for it to be worth the discomfort of the increased pressure on the ears when they're in, and also, I found that the largest tips sometimes don't get a good seal at all depending on how I put them in and sometimes I'll have to take them out and retry.
I'm now convinced the 75t is a victim of it's own success. It's passive noise cancelling was so good that the ANC brought little difference (to my ears). Comparing it to something like my wife's airpod pros, whose PNC was maybe like a 4/10 and ANC brought it to 8/10... The Jabra 75t PNC started off at like a 7/10 and ANC with the right tips, might have brought it to like a 7.2/10. For that minor difference, I'm personally electing to keep it off to save battery.
Still love my 75t though, and hey, can't complain about a free upgrade