They are such a standard response that presumably a real audiophile will come along to point out that their favorite model is much better, than a particular well known Sennheiser model, but as far as one can say in brand terms they are solid.
All the Chinese-made Sennheiser stuff has awful QA.
Also, there are multiple forums and subreddits you can ask this question on. You will get more answers than you would from me and the rest of HN.
Their build quality is exceptional, and they're built like tanks. The only problem, imo, is the Beyer house sound is very shouty and fatiguing, especially with the "990" versions of the product line over the years.
Disclaimer: I owned a Beyer DT880/600ohm (the neutral one of the 770/880/990 siblings), paired with an amp that could properly handle it. Its one of the few headphones I sold and did not retain in my collection, it deserved someone that could love it. The new Tesla-based drivers are better (such as that 1990), but still retain that Beyer sound.
Where'd you see they're exiting pro/flagship tier stuff? Everything I can find says they're continuing to hand-make their higher-end stuff in Germany. One such source: https://www.whathifi.com/headphones/100-year-old-headphone-b...
I recommend HiFiMan Sundara/Ananda if they fit your head and there aren't any CPU fans in your room.
Hifiman QA is exceptionally bad, and they tend to not stand by their warranty, and their US repair facility is just some dude's house.
The threads on /r/headphones over Hifiman shafting them are numerous.
Disclaimer: I too had a Hifiman pair, they sounded great, but their physical design just didn't hold up to daily use, no matter how much I babied them.
My best sounding headphones are a pair of old Stax with the worst construction I've ever seen on anything, so I mostly keep them locked up assuming they'll break if I breathe in them.
