If you are using next.js v19.0.2 and using the "Link" component with "field" the following markup is generated.
<a field="[object Object]">
...
</a>
This is a known issue of the version and it is fixed in some alpha release.
The v19.0.2 @sitecore-jss/sitecore-jss-nextjs
package incorrectly forwards the field prop to the HTML, causing invalid markup.
As you mentioned, this is a known issue with the JSS Nextjs SDK and is discussed in this JSS github issue: https://github.com/Sitecore/jss/issues/967
A solution has been provided via PR in https://github.com/Sitecore/jss/pull/929 which is due to be included in an upcoming v20 release of JSS.