I have a picture of the group from a BDB manufactured in 2017, where the same detachment of the protective layer that appears to be PTFE is observed.
It was cleaned regularly and at the last checks that layer was not detached, it just had slight irregularities (slightly bulging in places)

After so many years of use, a new group is required.
Or who knows, I like customization projects and maybe I’ll transform the brewing group, making one out of stainless steel. The only problem would be the more difficult heating with a stainless steel group, but I think it can be compensated with a more powerful heating element.
The BDB group has a heating element of only 100w and is thermally efficient. The entire espresso machine heats up from room temperature in just 4 minutes.
The device worked well over the years, without failures, only blue O-rings from the level probes were replaced on the steam boiler, and the interior hasn’t depreciated over time.






The coffee circuit water pump and the group gasket were also replaced. (The pump started to work inconsistently during pre-infusion with low power).
The group seems to be the only part that has depreciated over time, apart from the pump, which after a longer operating time is usually replaced.