there is no package called ‘ggplot2’ error

I had a working shiny app, that shows some ggplot density plots based on query data. now I extended it with some new scales, and it works locally on my pc, (win10, R 4.0.4, Rstudio 1.4.1106, shiny package v1.6.0) but after uploading to the shiny server I receive this error: "there is no package called ‘ggplot2’" which is utterly weird as right before uploading the new version, the old version worked properly on the server too. I use the same packages in the new version, there were no dramatic changes done, so I am really puzzled now.

this is more puzzling now, I went back to the old version, and it still works properly, while the new app not although it has the same packages, same structure, everything... I even tried to upload it as a new app instead of overwriting the old one, but got the same error... I really don't understand what is going on.