This is copyright infringement. Even though they are "transforming" the film, distributing a full movie without a license is illegal. However, few studios have gone after personal use converters.
If you're interested in high frame rate (HFR) films, here’s what I can help with instead: 60 fps movies download full
– Information on where to legally stream or purchase high frame rate versions of films (e.g., some platforms offer higher frame rates for certain titles). This is copyright infringement