Continuing the discussion from Ethernaut category, where @scammi compiled many solutions:
Video walk-through:
Status - Smart Contract Vulnerabilities: Ethernuats
Tim Holmes Mitra - Ethernaut Challenges playlist
David Wong - Ethernaut CTF walkthrough
Tinchoabbate walkthrough
Nicole Zhu series
Lvl 1 Fallback function
Lvl 2 Fallout
Lvl 3 Coin Flip
Lvl 4 Telephone
Lvl 5 Token
Lvl 6 Delegation
Lvl 7 Force
Lvl 8 Vault
Lvl 9 King
Lvl 10 Re-entrancy
Lvl 11 Elevator
Lvl 12 Privacy
Lvl 13 Gatekeeper 1
Lvl 14 Gatekeeper 2
Lvl 15 Naught Coin
Lvl 16 Preservation
Lvl 17 Locked
Lvl 18 Recovery
Lvl 19 MagicNumber
Igor Yalovoy
Ethernaut Alien Codex Solution
Tsauvajon
thispost
Lvl 20 Denial
Lvl 21 Shop
Lvl 22 Dex -> because the new user can attach 2 links in a post