If VHB tape is used by FWC to adhere the roof skin to the roof struts (rafters) I wonder which one, there are literally dozens of VHB tapes. They are designed for many specific applications. I have used a couple of different VHB tapes and found the adhesive very strong when the tape was applied correctly.
https://www.3m.com/3M/en_US/p/c/tapes/b/vhb/
I also cannot help but wonder if the temperature and humidity range the camper roof is subject to, and thus the tape, might be part of the issue by causing the tape adhesive for the particular tape used to fail either cohesively or adhesively over time and temperature/humidity extremes. There is a range of possible failure mechanisms including inadequate surface preparation, faulty material lots, etc that could be the root cause.
A full diagnosis would require disassembly and inspection by someone knowledgeable of structural adhesive tapes. Hopefully, FWC (or 3M advisors) performed lifecycle simulations over a wide range of temperatures and humidity with a roof panel adhered to roof struts before the engineering team employed VHB tape to adhere the one piece roof to the roof struts.
I am familiar with product development and it is not uncommon for design changes to experience unexpected failures after the product has been put in use even after structural/thermal modeling and scale model simulations appear to show success during the development phase. Indeed, lifecycle simulations are often not performed because of the time and cost involved. In fast paced development and analysis moving quickly into production environment that commercial products exist in, unexpected failures of new designs, even years later after real world vibration, temperature, and humidity cycling are always a risk.
It seems like a number of campers have experienced this problem. It is not clear from reading on this forum if it is just a few campers or a lot of campers or even campers of a particular model or range of years.
I encourage and hope everyone who experiences this problem (original owner or not) reports it to FWC. Hopefully FWC will collect that data by model and model year which might aid them in tracking down the issue, particularly if it is related to something like aging of the tape or particular year or model of camper. If it is a warranty issue that results in repair (and I have no idea if that is the case) then I would expect that FWC does reasonable investigations during repair to understand the root cause of the problem and if needed come up with a solution. The more people that report the issue the more likely FWC will understand the problem and a way to remedy it.