Hox to remove custom style from block when set to “default”

Hi,
I modified the core/paragraph style using the “register_block_style” function (server side) and set the new style to “default”. This worked fine. I then tried to remove the style using the “unregister_block_style” without success. Now, each new paragraph has this new style.
I saw on this forum (too late) that this problem had been reported earlier. Is it a known issue or maybe I did something wrong (although registering/unregistering looks very simple)?
Where is the new inline style registered? I could not find it in any wp folder or in the database. Thanks.