Version 3: used for code, launcher, or scripts. Allows remakes, but the source code must be published.
FAQ (detailed developer guidance): https://www.gnu.org/licenses/gpl-faq.html
Used for code or scripts. Very simple: fans only need to credit the author.
Used for code or scripts. Protects copyright, allows remakes and commercial use.
Used for artwork, logo, menu, and trailers.
Allows download and study, but no commercial use, no modification, and credit must be given.
Each mod has its own license (MIT, GPL, CC0, etc.).
Reference sources:
CurseForge: https://www.curseforge.com/minecraft/mc-mods
Modrinth: https://modrinth.com/