Discussions on fair distribution of costs, responsibility and spesific time limits seems to be called for.:
IF through specs, literature study+deduction and their lab tests, Leitz could and should have known that the spots would have developed, then they should replace or repair free of cost throughout a reasonable lifetime for the product. But what is a reasonable product life 10years? 50 years?
Digital devices of all kinds are after all usually consigned to the wastebin after a few years. So if a maker has taken all precautions, some of the burden, after some years have passed, should perhaps fall on buyers aquiring a new, untried product, even if it comes from a reputable vendor. The question then becomes: more buyer responsibility for covering costs after 3years? 5 years? 30%? 50%.of costs?
Look at more ancient troubles: a Leicaflex SL may have a slight beginning yellow cast to the viewfinder due to the prism coatings used and its meter may be sluggish, but customers will probably agree that it is not fair to ask Leica\ Leitz to take care of that for free. A CL may have very slow slow speeds, and like any ancient shutter will need maintenance, but free repairs?.
I recently had my 35-70\4 -R suddenly stick. Solms repaired it and I paid and was happy that it was fixed. No idea whether the cause was an unlikely coincidence or if the internal cams had worn too fast due to the turn of the century engineers being too optimistic. I did appreciate that there still is a service that can keep R-optics alive- even if one has to pay.
What one should demand, however, is total repairability of all products that they have made in-house. DMR parts and out of production ICs excepted ( but much can be designed anew. After all, vintage and classic cars still have modern pieces put in. )
Canon and Nikon make excuses "not feasible to keep spares after 10years". Aspiring to be world leading, Leitz\Leica should be able to make bespoke pieces to repair anything they make. and keep the skilled workforce to do so.
p.