Acquiring pixel data from TIFF-file into CSV-file in QGIS

I have a TIFF-file which gives me a value of forest age per pixel in the whole Amazon basin.
I am trying to do a spatial-statistical analysis between forest age and climatic variables.
For this my goal is to have an attribute table that shows the forest age, climate variable, lat/long per pixel.

This TIFF file did not come with a text file or CSV, and I am not able to extract an adequate attribute table.

How can I acquire a CSV file with all the pixels values in QGIS for my study area? (age of forest, lat/lon, etc.)