""...and join the fight against the takedowns!"

Recently, Gmod's Steam Workshop has been struck by multiple DMCA takedowns mainly targeting addons that are related to Nintendo, originally people thought it's a series of false reports made by a guy known as "Aaron Peters", but the official announcement and Garry's statement on Twitter made some people believe that the takedowns were made by Nintendo themselves, however there are some reports of non-Nintendo addons getting taken down as well.

Not matter who's the is real perpetrator, The Steam Workshop isn't safe for addons anymore, thus I recommend a few alternatives sites for you to upload your mods up to besides the Steam Workshop:
Internet Archive (Slow to upload and old site structure, but ensures the preservation of the files.)
https://archive.org/
GameMaps (Old mod site, the main place to get L4D2 mods before the workshop is a thing.)
https://www.gamemaps.com/
SFMLab (Mainly for SFM, but can host Gmod models as well as long as they're usable in SFM.)
https://sfmlab.com/

And Telegram as well, as it has a virtually unlimited cloud storage for you to upload your files up to, and bots to make them downloadable for others.
https://telegram.org/

You can use both Crowbar and gmpublisher to get the addon files from the workshop.
(Too bad SteamWorkshopDownloader.io isn't a thing anymore, sad.)"