I’d suggest you search the forum for this issue. You may need to be sat down with a long drink, there are many pages.
My own experience is with our 2019 model. After 18 months we had the dreaded blisters. The roof was replaced under warranty.
Less than 6 months later the new roof has blisters.
Luckily it was reported to MB while still in warranty and a second roof is on order. Others on the forum haven’t been as lucky.
It’s worrying that your 2021 model has the same problem.We are selling our MP. As much as we love it we simply don’t want to own it out of warranty.