Password reuse is a very different issue. You should not be reusing passwords on accounts you care about period. 2FA isn't meant to protect against reuse (though it does help). If a password is reused your 2FA becomes just 1 factor.
This does not make reuse more dangerous either. An attacker with a leaked password list will try them against known sites anyways. If they wanted to try a leaked password against Walmart they'd have done it regardless of the 2FA signal. There's no reason to assume that if a password is (in)correct on one site that it would (not) be on another. The information of whether a password worked or not on a site means nothing to someone trying to hack your account.
Also 2FA sites do do this already. Google and Amazon both do this along with many others (and increasingly many). Also it does not have to force a password reset. A notification email about an attempt is sufficient, you can decide for yourself whether it was you or a suspicious attacker.
This does not make reuse more dangerous either. An attacker with a leaked password list will try them against known sites anyways. If they wanted to try a leaked password against Walmart they'd have done it regardless of the 2FA signal. There's no reason to assume that if a password is (in)correct on one site that it would (not) be on another. The information of whether a password worked or not on a site means nothing to someone trying to hack your account.
Also 2FA sites do do this already. Google and Amazon both do this along with many others (and increasingly many). Also it does not have to force a password reset. A notification email about an attempt is sufficient, you can decide for yourself whether it was you or a suspicious attacker.