I don’t think this was ever intended to work. I’ve not come across it in the documentation. It seems to have been a bug that has been corrected.
To access states using mustache templates you would use
{{entity.sensor.inverter_dzienna_produkcja}}
https://zachowj.github.io/node-red-contrib-home-assistant-websocket/guide/mustache-templates.html
Mustache templates are limited in use, jsonata is native to nodered and will give you more flexibility especially with numbers.