Genuine question as i dont know but do Teslas have an actual traffic sign recognition camera or is it all based on the database?
Its a bit of both and history involved.
The original Tesla Autopilot system, typically referred to as AP1, was based on the third party Mobileye system. It could do speed limit sign recognition and was apparently very good at it. For whatever reason, Tesla and Mobileye parted company with Tesla going it alone with many premature promises as to when parity would be achieved. Roll on Tesla Autopilot AP2. AP2.5 and now AP3 as they are typically referred, the latter being based on HW3 aka the 'FSD computer'. Due to Mobileye apparently holding patents in speed limit sign recognition (reality was it was more complex than just patents which were very specific in their method), Tesla AP speed limit detection was wholly based on maps.
AP3 bought in significant changes to object detection and visualisation, the first being traffic cones at the end of 2019. I believe that some limited forms of this has been retrospectively applied to AP2.5. I think that traffic cones was really an exercise in Tesla showing that they can both identify and pretty accurately locate fairly small objects. Roll on mid/late 2020, Tesla started to introduce vision based speed limit detection in certain circumstances and only on HW3.
How things stand at present is that visual speed limit detection is for 'local roads' only - how you interpret that is anyone's guess, but if you assumed that excluded Motorways and/or any NOA (an EAP/FSD only feature) enabled roads, you probably wouldn't be far off.
So that section of A319 road is covered under visual speed limit detection, until the system gets itself in a position where it needs some assurance, in which case it reverts to GPS/map based detection. This actually occurs immediately past this junction, as the moment the car realises that the incorrect 40 no longer applies it reverts to an incorrect NSL/60 limit - presumably the map data pre dates the road being changed to 50 several years back.
So what we have is a system that knows exactly where it is, knows exactly what route the car is navigating, knows exactly where the speed signs are yet cannot work out that the speed limits do not apply to the route that the car is driving on. Now, this would be understandable if the car was a bit more basic, but if that section of road was being driven on full autopilot (I'm not stupid enough to try it as I know it would end in tears), it would very likely respond to the incorrect speed limit changes. And its certainly a very basic function needed for FSD. Unfortunately, its not unknown for the car to phantom brake when on high speed roads such as Motorways (so no visual detection going on) because the car has incorrectly used the speed limit for an adjacent junction/intersection.