Les paul series piano patents exist, but the appearance patent has a protection period. During the protection period, Gibson can sue the manufacturer if the manufacturer produces pianos with similar appearance, but after the validity period, he can't control others, which is why Gibson and prs lost the case.
But les paul's patent for piano is still valid. You can produce a piano in the shape of les paul, but this piano can't be called les paul. If you scream, it will be infringement. Therefore, although there are many les paul pianos, only Gibson and Epiphone can write les paul on the piano head.