See: Re: ANNOUNCING GENERAL AVAILABILITY OF NPM 10.7
Someone with decided that adding extraneous text identifying a custom property as such was a good idea.
It is not; this change should be reverted
It should be noted that the most voluble complaints about new UI changes have always been around custom properties. For those of us with large networks (more than 10,000 objects) these are essential for us to manage our infrastructures. Changes to the UI around custom properties should always be explicitly included in the release notes for beta and release candidates.
Thanks