Your drugs maybe?
Okay, just kidding… nothing’s been changed!
It makes perfect sense to use volume leveling to adjust individual title’s absolute levels in order for the median loudness to stay around a set target level to prevent perceived loudness jumps between songs.
Roon’s nomenclature sticks with the E(uropean)B(roadcast)U(nion) standard for their average dynamic range display and L(oudness)U(nits)F(ull)S(cale) target, that’s been introduced to standardize radio programme mixing.
Of course, in most cases the effect is that the music sounds “lower”, since their level need be lowered for above reasons.
If it’s too low a volume for you, just twist your knob up to liking.
It does not affect dynamics, since it’s just a fixed level offset per song or album.
In Roon volume calculations are done with 64 bit precision, correlating to a dynamic range of 384dB.
So no worries, any artifact introduced is many orders of magnitude below what any amp or human perception may be able to resolve.