Disable highlights from MASS NICK SPAM?

put https://svetlana.nfshost.com/free/Downloads/hexchat/masshighlightignore.lua into %appdata%\HexChat\addons or ~/.config/hexchat/addons (modified version of masshighlightignore.lua shipped with hexchat)

Modified original -- added licence header. Link to original: https://github.com/TingPing/plugins/blob/master/HexChat/masshighlightignore.lua

Hide MASS NICK SPAM from screen completely?

put https://svetlana.nfshost.com/free/Downloads/hexchat/massnickspamignore.lua into %appdata%\HexChat\addons or ~/.config/hexchat/addons (modified version of masshighlightignore.lua shipped with hexchat)

Modified original -- added licence header and commented out the line which prints the spammy message out.