anyhow, to address the original statement.
Getting over 30 Knots really is not that hard if you have:
1.
Flat water (so you can bear away at the best angle, in control and with minimal drag)
2. 20'ish+ knots of wind
3. A modern smaller to mid size slalom board and powered by a modern Freeride/Freerace/Slalom rig to suit for your size.
So I would say the obvious thing in this case is that you are missing one of those 3 things, and since 2 and 3 seem to be covered, it looks like you don't have flat enough water.
Here is a video from 2021 on really flat water at Lake George, South Australia. I averaged just over 30 knots for this Nautical Mile almost effortlessly, on an Isonic 80 (2017), Ka 5.7m Koncept/Speed sail, 20cm Atomic Nuclear weed delta fin. The wind was dead south average (183 degrees- confirmed on the Polar Plot). The measured angle from the GPS track is right around 115 degrees off the 'average' wind with only a few degrees variation either way at most. The wind in this run was no more than 20 -22 knots in the gusts, and mid to high teens in the Lulls. I have had considerable experience in this situation learning the optimum angle to sail, and this definitely was it. Any broader and I lost speed and pressure (confirmed in real time by my speed talk app), even in the slight gusts. Note that it was not very windy for this size gear. It took a while to get planing at the start. I am about 75Kg in my sailing gear. Most sailors this day were on larger gear. My second best peak 2 second speed of the session (33.85 Knots) was during this run. The max 2 sec for this session (34.2K) (Top center of the map) was on the other tack and was in a freak puff of maybe 25 knots, and probably in a wind shift, as it looks way too broad on the trackmap for this amount of wind strength.
The polar plot of max speeds for this session is very deceiving, and it suggests that those speeds were
very broad, when in fact they were no more than 120 degrees off the wind. I think this is an artefact of the normal variation in wind direction of probably 10 to 15 degrees from average, especially in the gusts where max speeds are sought out, but I wonder if the plot is affected by the Gybes as well?

Here is the session track with the NM highlighted:

Video of this run with Telemetry (knots):