Question : table consume disk space

Hello,
I do not know if it's the way to ask a question on this project, if not sorry about that.
I'm using Debian GNU/Linux 12 (bookworm), Kernel Linux debian 6.1.0-9-amd64, PostgreSQL 15 from package 15.3-0+deb12u1, and the package postgresql-15-hll extension from package 2.17-1+b1.
We would like to see the result of the cardinality after adding a lot of UUID in using the function "hll_add(hll, hll_hash_bytea(?)) with a binary uuid", and I see that my disk space is consumed by the table.
Do you have any idea why, even if the HLL record is small (few kb), the result of "\d+" command and the size on disk can reach several Mb ? Do I have to configure PostgreSQL with dedicated parameters or do something else to not have this issue ?
Thanks a lot in advance