This is tagged with local_ref=60 and is therefore presumably a right of way under the responsibility of the local council (Harrow?). Unless the council has officially re-routed the footpath, it's the responsibility of the council to ensure whoever owns the land removes the overgrowth to keep it passable. So I suggest you ask the Council to perform its statutory duty by taking  enforcement action, as described at https://www.gov.uk/guidance/public-rights-of-way-local-authority-responsibilities.

I have provisionally added the tag obstacle=vegetation to the section by your marker, but this is documented as being not an official tag so it's probable that routers will ignore it.

Your suggested alternative route (via footpath 61 and part of footpath 59) is already mapped.

The best answer by far is to persuade the council to do their statutory duty and get the path cleared.

Once they have done this, please update us here so we can remove the obstruction tag.