Large video files in Google Drive or high-quality backups in Google Photos are common culprits for a "full" inbox.
Most people don't realize their storage is shared. You can see exactly what is taking up space at Google One Storage 2. Mass-Delete "Temporary" Clutter gmail temp mail full
Mozilla offers email masks. You can generate five random email addresses that forward to your Gmail. If they start spamming you, you turn off the mask. Large video files in Google Drive or high-quality