If you use this images storage service surely you will know that you can store your photos and video without occupying space on Google cloud in exchange of limiting the size of these to 16 megapixels. If the photo has more than that resolution, Google reduces them to that size. In the case of RAW files the same procedure is performed, the service uploads a file in Jpeg format of the RAW photo, limiting its maximum resolution to 16 megapixels.
Google Photos has an unlimited storage mode for free and another that consumes space. This mode is called High quality, but if you use Google Photos on many devices, including uploading your library using the programs available for Windows and Mac. It is possible that at some point you have not noticed that in any of those devices you had activated the original Quality mode.
In that mode the photo is uploaded without altering its size or any of its properties, but in exchange you are taking up storage space in your account. To know if this is your case go to Google Drive and click on the option Acquire more storage. The space that you are consuming on each of your Google services will appear: Gmail, Drive and Photos. If you have never stored photos with original quality in Google Photos, this service should not be consuming storage space.
If you see that Google Photos is occupying a part of your storage space, the solution is not to go looking for photo by photo until you find the ones you como across with their original quality. There is a much simpler solution. To activate it go to the Google Photos settings from the computer’s browser (if you use a mobile or tablet you can do it from Chrome by activating the computer mode). In the settings you will see if you have activated the original quality mode or the high quality mode.
If everything is correct, but at some point you updated inadvertently, or forgot to deactivate the original quality mode click on the Recover Store option. This allows you to compress all the photos and videos that are occupying storage space in Google Photos.