Solved!

First riddle (this one): tiberium - the Tiberium crystal from the Command & Conquer Tiberium universe https://cnc.fandom.com/wiki/Tiberium. It can be green or blue, and it's highly toxic.

Second riddle: kobe/koube - both work - https://myanimelist.net/character/134257/Shio_Koube. Her name is "Salt" in Japanese but she's the opposite of that (sweet, so "sugar"), Happy Sugar Life is on the first page when you google "Who is salt but actually sugar? (hint: related to anime)". The whole anime is kind of centered on this word play between Satou and Shio being the opposite of their names.

Third riddle: A Base32 string in the image metadata
"LFXXKIDHN52CA2LUEEQFAYLTON3W64TEEB2G6IDUNBSSA4DBON2GKORAPI2HU6SIKVBXI5TPGBLQ===="
Decodes to:
"You got it! Password to the paste: z4zzHUCtvo0W"

Yes, the QR code has absolutely nothing to do with the answer, it's just a cool song.
I added it because I thought that just a normal image with nothing else on the page will make it too easy to guess that it's in the metadata.

I glow with a hue, both green and blue, From another world, some say it's true. In games I'm sought, for power I'm bought, Yet touch me not, or harm be wrought.

I'm not a gem, though shine like them, In fields and mines, I'm the stem. What am I, this radiant bloom? Speak my name, or meet your doom.

All lowercase. When you get the answer, go to
rentry.org/61363af04283ec0d045ac05e7ac19aae_answer
e.g. rentry.org/61363af04283ec0d045ac05e7ac19aae_word

Paste link with the token (to get the token or to check if it was taken or not):
https://safenote.co/r/64cb2e1744bb67@27608745