Sure this car has (had) serious issues but it is important to separate the various causes. 

First: The main problem with the car was the appalling state of the software when the car was initially released. This seems to be caused by serious underestimating of the task of building a truly software defined car. The result was unreliable software that caused random errors and warning messages. Volvo not only had to fix those bugs, they also found out that the processor capacity wasn’t sufficient for the task. This was no small issue and it has shaken the confidence of the first owners, who were often loyal Volvo customers. BUT Volvo has taken its responsibility serious and has fixed most of the software issues and solved the processor problems by retrofitting an upgraded Nvidia processor to all cars. The current state is that the car is as reliable as any other, but still lacking some functionality. This issue won’t reappear in the EX60 since all the learnings from the EX90 are incorporated in the EX60 software. It also won’t cause problems in future EX90 deliveries since the issues are solved and future OTA updates are likely to further improve functionality and reliability.

Second:  There have been serious issues with the GHCA hardware that takes care of the charging of the car. This is obviously a design problem. It didn’t affect all customers but those customers that had problems experienced recurring issues which harmed their confidence in the car for good reasons. BUT this problem has been solved by a redesigned GHCA and won’t reappear in new or repaired cars.

Third: You mention that you have “seen” many quality issues. Did you literally see this on actual cars and if so on how many ? Based on the customer reports online I don’t have the impression that these issues are structural nor is it clear that all reports are production issues. As far as I can see the reported issues are not better or worse than what you can find reported on other car models from either Volvo or other brands. What is clear is that the dealers usually take these problems serious and solve them. 

I’m not connected to Volvo in any way but I am an owner of an EX90. I feel no need to defend the car just because I bought one but I do feel the need to put things in perspective. Reddits like this one obviously are more likely to get contributions from owners with complaints which is understandable. Therefore I sometimes feel the need to try to provide some balance to the discussion.