'Can this FoV changer cause a ban from Valve Anti-Cheat?'
Sure, the PC devs might randomly start cracking down on people changing their FOVs, but in the 2 months the game has been out, they've done nothing to suggest they care about FOV on PC. Also, the FOV fixer in the link has a script that checks if anyone has told the creator that they've been banned. This tool has been out for more than a month, and the older 'Widescreen Fixer' has been out since the game launched: so far, no bans have been reported for either tool.
