Met with customer and spoke with them regarding the issue they are experiencing. Customer has whole home backup and first noticed the issue roughly a month ago. Customer has been in and out of the home and using fixtures infrequently. But recently when they used fixtures upstairs it caused their toilets to gurgle as well as downstairs. Home was built in 2023 and is on concrete slab. There is a clean out outside where sewage came out of and the clean out is currently full. Clean out is only about 10-12’ from the septic tank lid. I recommended to the customer that they contact a septic company to remove the lid and pump the tank out as it is likely full. Customer will do so and a sewer supervisor will return to the home Friday to camera inspect the line after the tank is pumped to ensure there are no issues with the piping from the house to the tank.