When your pipes start to drain more slowly and everything starts to back up, you want to do what you can to get the pipes cleared so that your drain will work normally again. The best way to do that is to call a plumber. They can come to your house and look at your drains to see what the issue is. There are various ways that the plumber can do this. One of them is to send a camera through the pipes to see if they can find the problem. If they can't find the problem in your house, the plumber will have to look at the pipes outside to see if they can find the problem. One big problem that you might have is roots in your pipes.
The primary job of any plant's roots is to help get nutrients out of the ground and up into the plant. A root can sense moisture and will start to grow in that direction to get that water into the plant. Your pipes can be a good source of moisture and nutrients for the plants, and the roots will break into the pipes and eventually fill up the pipes, and nothing will be able to get past the pipes. It doesn't happen immediately. It will take some time. That means you generally don't notice the problem until it gets significant. If roots in your pipes are the problem, your plumber will have to clear them out. There are several ways to do that, but one of them is relatively non-invasive.
One way to do it is to send a high-pressure water hose through the pipes. The hose will have a waterjet nozzle on it. The nozzle will send a very narrow and high-pressure stream of water out, and when it reaches something like roots or other blockages, the jet nozzle will break through the roots or blockage to let the pipes work again. It may take some time for the plumber to cut through the blockage, depending on how severe it is and how far into your pipes it is, but it should eventually get cleared out. Once it is clear, the plumber can send a special pipe up through the break to seal it off and try to keep more roots from getting into your pipes.
If your pipes are draining slowly, you might have roots that have grown into your plumbing. Talk to a plumber about checking your pipes and clearing them with a waterjet.