As I have already mentioned, the issue has been tested without using Optifine. The fishing line still doesn't detach after lying on a bed.
Issue tested without using Optifine, still "works" - the line doesn't detach even if in a bed.
Okay mates, thank you for telling me, I will check the issue on unmodded Minecraft 1.15.2.
Matej Grega
As I have already mentioned, the issue has been tested without using Optifine. The fishing line still doesn't detach after lying on a bed.