Node.js support is installed in Plesk.
After changing the Node.js version in Tools & Settings > Updates, the previous version is still shown in Domains > example.com > Node.js.
Bug #EXTNODEJS-35, which will be fixed in future product updates.
The issue is purely cosmetic and affects only the Node.js version shown in Plesk interface.
Until a fix became available, perform the following to update current Node.js value in Plesk interface:
Click the Refresh button in Extensions > My Extensions > Node.js [Open].