Anyway, after a few weeks already massive traces of oxidation and total failures.
A big plus:
Without much discussion and money there was a replacement for the defective light strips.
Experiment No. 2:
I have the strip now generously sealed at the edges with AQ Silicone / smeared / glued.
I wait from now, if that is sufficient. If so, would the remaining criticism that the installation can only be achieved with additional silicone and therefore no longer simply and quickly.