Steam followed games number can't match

Maybe try steamdb, use the extension, go to sales and check the followed checkbox and adjust the filters accordingly so it shows any possible game. Then once you find them, you can go to their respective steamdb page and unfollow there. My only guess.

Pretty sure they're removed games so they wont show up on the steam page anymore, so no way to unfollow from there I believe or figure out which they are.

I do find one game which didn't show on my followed games page, since it was removed. I have no idea on how to unfollow it

My pal edited a series of codes, just need to stay at https://steamcommunity.com/id/XXX/followedgames, use console by F12, paste the codes, find all and delete there games with 1-click.
Issue solved, thank you

var show = [];
document.querySelectorAll('div.followed').forEach(node => show.push(parseInt(node.getAttribute('data-appid'))));
fetch('https://store.steampowered.com/dynamicstore/userdata/', {credentials: "include"}).then(res => res.json()).then(res => {
res.rgFollowedApps.forEach(appid => {
if (!show.includes(appid)) {
console.log(appid);
fetch(https://steamcommunity.com/app/${appid}/stopfollowing, {method: "POST", credentials: "include", body: sessionid=${g_sessionID}, headers: {"Content-Type": "application/x-www-form-urlencoded"}});
}
});
});
console.log('finish!');