We constantly use the plugin for bands downscaling instead of simple resamplings.
After SNAP 9 and Sen2Res ver 1.1. and the use of L2 Sentinel 2 products with the new folder structure, the results on B1 are bad visually but also quantitatively.
Unfortunatelly, Sen2res is a third party plugin, not maintained by SNAP team.
It was developed by @nicolas.brodu, you can see below.
There is no newer version of this plugin that could take into account the new Sentinel-2 format products.
I know that is a third party plugin which does amazing qualitative work. However, Nicolas does not maintain the plugin following the new developments of ESA on the product format, hence now is useless, unless ESA wanna make it work by incorporating in its standard tool.