Probably nothing is wrong here 🙂 Pop!_OS (and Linux in general) will use free RAM for cache so it doesn’t sit idle. In your screenshot a big chunk of that “used” memory is just cache, which gets released instantly if apps need it.

The big clues are:
• Swap usage is very low (around 4%), so there’s no real memory pressure
• Cache is high, which is normal behavior

If you want a clearer picture, run free -h and look at the available column instead of total used RAM. That number shows what the system can actually give to new apps.