Same been months since i tried and get the same error

Use PC client only no mobil and stop spam the try effect

"too many requests how can i fix that"

Try1 time every 3 day to get ride of the cooldown counts you have.

We arew steam user here, we do not have steam insights why this is so, and what prevent them not to change it, if they feel its like a DOS attack.

Feel free to ask steam support about it.

Make sure no other is using your account login and pw. or whatever remote device you might have used. ( i try reduce your hamemer the service, also why "too many requests" according to steam effect you.

Steam Login history
https://help.steampowered.com/en/login/?redir=%2Fen%2Faccountdata%2FSteamLoginHistory&need_password=1

Thirdpart login
https://help.steampowered.com/en/login/?redir=%2Fen%2Faccountdata%2FThirdPartyLogins&need_password=1

Other issue.

Authorized Devices
https://store.steampowered.com/account/authorizeddevices

Check its only you that is on the account and allowed.

ps.
Do not have past windows if this is service issue that is now only win10+, just incase this matters,

Keep in mind i only read "too many requests" if no other steam users has any ideas, try contact steam support and explan, you do not hammer the site or had too many requests.

Only steam can check how is this even possible.