This is a solo piece for clarinet.
It is part of Gebhard Ullmann's series of solo compositions for woodwind instruments from 2020.
4 pieces originally for bass clarinet, this one has been completely revised for clarinet 2021 and originally was No 3 of the bassclarinet solo pieces.
(the sound sample is included to give you an idea.
It is a demo version as being played by Sibelius)