Uninstalled still show up

​@Todberez If you are using a MAC, clear the internal font cache specifically for Photoshop, start by closing all Adobe applications (better yet, close every single app) to ensure no files are currently in use. Open Finder, press Cmd Shift G, and paste the path ~/Library/Application Support/Adobe/Adobe Photoshop (Beta) to jump directly to the application's support folder. From there, locate the folder titled CT Font Cache, move its entire contents to the Trash, and empty it before restarting Photoshop to allow the software to rebuild its font database from scratch. Don’t worry, a new set will be created
 

I be very surprised if this doesn’t clear it. and if so, go back to Finder, press Cmd Shift G, and paste the path ~/Library/Application Support/Adobe/Adobe Photoshop (Beta) to jump directly to the application's support folder. From there, locate the folder titled FontFeatureCache

If the issue persists, Adobe also utilizes a "DeepFont" cache for its machine-learning font recognition features, which can sometimes get stuck, by deleting the Deepfont folder inside this directory can often resolve "phantom" font issues where Photoshop thinks an old version of a font is still active. Empty th trash before restarting Photoshop to allow the software to rebuild its font database from scratch. Don’t worry, a new set will be created

If that still doesn’t work,  open Font Book, Select Montserrat and right-click and select Resolve Duplicates. Even better: Use the Validate Font tool (under the File menu) to see if there is a "structure" or "naming" error. If "Montserrat Alternates" used the same internal PostScript name as "Montserrat" in its metadata, Photoshop will default to whichever it saw first.

​@Todberez “This only happens in PS Beta” you’d be better off reporting the issue in the Photoshop Beta forum