Perhaps you are right, and I had rose tinted glasses. I seem to remember C++17 being completed (all major features) around 2018 on at least one or two major compilers. Meanwhile C++20 still doesn't have modules properly implemented, which is such a huge feature IMO that I count it as a major deficit. But maybe C++17 was the exception rather than the rule.

I think what annoys me most is when a standard is implemented except for an important feature. E.g. ranges was unusable for ages on Clang. And modules is still not quite there. I want to use the latest standard to get these cool features so I can write code like it's 2025, not 1980. If the biggest features are unimplemented then why upgrade? My concern is the trend continues, and we get cool things like reflection, but it takes 10 years to be implemented properly.