It doesn't really matter if a unit is Pre-Covid, Covid, or Post-Covid, with any pre-owned camper, the current condition all depends upon how well the previous owner(s) took care and maintained maintenance on the unit up to this very moment.
Yes, Covid era campers had their problems. But, folks who purchased them went through nightmares to get them fixed and fixed right. Now, most of the issues are resolved, or those campers have been hauled away to junk yards.
In the end, a pre-owned camper's current conditional all depends upon how well, how much attention, and how much money the previous owner was willing to invest in it. No matter what you choose, you'll need it inspect it thoroughly. There WILL be issues with anything you purchase (brand new or 50 years old), but only you can determine if you are willing to invest in fixing those issues or if you can live them. If you are not willing to invest yourself into the camper, no matter how new it is, or how perfect it is when you get it, if you don't invest it will be junk in a very, very short time. They ALL demand work.... lots of work to keep them nice.