Technically Valve covered their ass with a vague SSA statement

You agree that you will not use IP proxying or other methods to disguise the place of your residence, whether to circumvent geographical restrictions on game content, to order or purchase at pricing not applicable to your geography, or for any other purpose.

But realistically restrictions only apply to purchases. Even then it's kind of iffy, plenty of people still abuse VPNs to get lower prices even after all the changes and they have no issues with it.

Here's what Steam Support had to say about VPNs five years ago:

Hello,

Playing games or operating Steam while using a VPN is not strictly prohibited.

However, it may affect gameplay and the Steam client itself.

A Steam account will only be restricted for actions that violate the Steam Subscriber Agreement or Steam Online Conduct Rules, so please keep in mind that purchasing games while your VPN is active is a violation of our Terms of Service.

If you have any further questions, please let us know - we will be happy to assist you.

Maybe Valve's stance has changed since then but I've not asked support about it. I'd be interested to know if anyone talked with Steam Support recently about VPNs and what's their current stance on this.