I recently had this problem too!
The solution was to type:
lib_deps = envirodiy/EnviroDIY_ModularSensors@0.28.1
So, drop the “0”. Everything worked well, and it properly fetched v0.28.01.
I’m not sure why Sara added that 0 to this version, but I suspect is was for a reason, but unfortunately the PlatformIO library registry doesn’t like having that 0 there.