Hi, we had the same problem on our Lavezzi 2 years ago.
What is happening is that due to the huge size of the window the difference in thermal growth between the fiberglass
and the Acrylic window when heated up works away the Sicaflex which is used to glue the window on.
The foam rubber is just a seal towards the inside of the saloon
to give a nice clean edge.
The only solutiuon to this is to cut out the window completely, clean and prime the window as well as the gluing edge on the cutout, and add a new 8-10mm thick self adhesive
foamed rubber gasket
around the window cutout onto the fiberglass
around that rubber gasket
you have to make a bead of ca 20x20mm of Sicaflex 295UV and place the window with the help of 8 4x40mm woodscrews through the existing mounting holes in the window.
You need to be careful to not compress the rubber band to smaller then 8mm, because you will need to have this thickness off bead remaining to leave enough play to compensate the different thermal behavior of the materials.
We achieved that by using some 8mm spacers on the edge.
was done in April 2021, and we have sailed some 5000nm since then without any problems.
It is a lot of work
(it took the two of us nearly a week to do it), but it is looking exactly as before....and now I can trust the gluing of the window and can be sure that it does not fall off in case of a big movement of the boat
in big waves
The Starbord window is less critical because it is smaller, but to feel safe I plan to redo the glue on this also in the next winter