Reeder S19 Max and P13 Blue Plus 4 Persistent Lag Issues

I have a Reeder S19 Max 64 GB and a P13 Blue Plus 4 phone, and both of them are having some lag problems. I've brought up this issue before, and they said they would replace the phones, but it seems like all four of them have the same lag issue or I have to pay extra to get an upgrade. I'm not allowed to return them, and their solution is to stop running background apps. I'd like to return these phones. The phone brand is failing to meet my expectations and is not taking any action to address the issue. I'm looking for a solution, and if it comes down to it, I'm willing to pursue legal action. I'll continue expressing my grievances here for everyone to witness. Let them see just how disappointing and embarrassing this situation can be. I wouldn't suggest them to anyone.