I think the probable sequence of events was;
1) VW had a long established supplier for bellows, who was either located in, or had direct supply lines to, either Russia, Russian allies or war-torn parts of Ukraine
2) VW then had to identify a new supply chain partner who could produce the bellows
3) The effect wasn't noticeable to consumers immediately owing to stock levels at distribution centres/factory and elsewhere, hence why the problem surfaced around a year ago or so (possibly a longer timescale due to slow output of the factory)
4) New supplier and/or materials provider either had to come up with a new design from scratch, and/or had different materials available - either way, this caused a departure from the existing design
5) Evidently the new design has flaws that may have not been apparent in product development (which was likely to be rushed anyway if it was severance of the existing supply chain that caused the problem in the first place)
I have no evidence for this, just conjecture, but I think it's very unlikely VW would change the material as an "incremental improvement" in a vehicle that sells well and is on final approach for wrap up of production. My guess is their hand was forced, everything was rushed and we're seeing the results of something that hasn't been through the full design and development process being pushed out to consumers.
It's an interesting theory but not really how things work in an OEM. To pickup your points in turn;
1 - Maybe. I don't know who the 1st or second tier suppliers are for VW, just my old employer. Most larger parts for any OEM are made on a JIT basis, so it is possible the actual production site for the bellows is very close to Hannover.
2 - Maybe again but the issue with bellows is directly related to a complete change of design from a single to a double skin as part of the MY23 changes that were implemented in VW in Sept 22. As far as we can see from all the various threads, eventually all new bellows are affected.
3 - See above. It was a full design change to a new type of bellows that was the infliction point. It looks like the main reason for the change was to reduce light in the pop top and increase thermal efficiency. Both guesses, but they are the net effect of the new design.
4 - 1st and 2nd tier suppliers MAY have input into design, but all designs for all parts is led by and comes from VW design centres. Was the same at my old employer. When a part is locked it goes out to tender to a number of suppliers who then compete for the lowest cost. This may have had some bearing on the quality of the bellows, and it's issues, but not usually the design.
5 - Yes to the first part but it is unlikely in my view that the war in Ukraine is the effect on this. Design and parts buy offs are lengthy processes for legal and practical reasons.
I could say that I have a mate in Germany and VW that is telling me all the above, but I'd be lying. I do have some friends in VW UK, but they would not give me any info if I asked (as I would not have done either in my old job) for legal reasons. I do also have a friend in the auto press who I have informed about this and he has a friend in the camper van magazine world, but whether any of them want to upset their relationship with VW is another thing.
