GLFW 3.5.1 was released, skipping 3.5 due to my mistake which resulted in 3.5 being tagged [1]. This is primarily a bugfix release.
https://github.com/glfw/glfw/releases/tag/3.5.1
[1] I pulled a PR branch for an investigation which the user had tagged with 3.5, then deleted that branch. When pushing another branch I didn't realise 'push tags' was on in the tool (I had pushed tags for another repo just before). I also didn't realise tags could be pushed which were not on any branch.