Well I play the sims 4 a lot including this game called Roblox and the arrow keys are doing the same thing on both of the games. And I got the sims 4 on steam and roblox on its own website. And I don’t really know the exact model but I think it’s has a 4.00 GB Ram and a 64 hit processor or something that’s all I know and it’s a windows 10.
4 GB of RAM is probably not enough for The Sims 4. I don't think it's even enough for The Sims 3, since saving becomes an issue. I would recommend upgrading your RAM to at least 8 GB.
I think it's wrong that they still sell PCs with 4 GB of RAM in 2021, but that's just my opinion.
But mid-game, it sounds more like a processing issue or graphic processing issue. Your CPU/GPU may just not be powerful enough, either. But we don't know which CPU and GPU you have.
To find your system specs, open Settings- System-Scroll down the left panel to About.
To find your PC model, if your PC is a laptop, it should say the model next to "Model:" on the bottom panel of the laptop. And the laptop's brand, well, that should definitely appear somewhere.
If it's a desktop, it's on the top or sides of the computer tower. Assuming it's not a home-built tower. Sometimes it is on the back, maybe, but I've never seen that.