There is language innovation in Common Lisp, but it's either things that need to be in the standard (example: package local nicknames) or in improved implementation of things in the standard.

The latter one I point to often is the problem of efficiently compiling a dynamic language, where (for example) the offsets of slots in objects can be changed at run time, or (another example) where the set of methods for a generic function can change at run time.

See Robert Strandh's paper in https://european-lisp-symposium.org/static/proceedings/2021.... (page 72)