Lucky it was closed, if it just got wet on the bottom you probably can take it apart and clean it with isopropyl and it will be fine. Just make sure not to miss any spots where coffee ingress.

If you can’t do it, a competent shop should be able to.

Bullets

Use wifi and ruin the signal.
Or limit your bandwidth

There are hundreds of reasons for why. Without additional information the only thing we can do is guess and make basic suggestions.

Share more information or try clearing cmos / disabling OC settings / lower ram speed.

don’t play on wifi, enable QoS

While true, it’s still best practice to move it to GPU.

No, you just revealed to yourself that you’ve bveen using the wrong video output this whole time. It’s ok to use the integrated one in the motherboard for secondary monitors and such, but the primary monitor should be plugged into the GPU itself. If you don’t have the right cable get one or an adapter. You’ve basically been idling your video card. Prepare for a world of difference once you get it plugged in correctly.

There’s a reason, probably the power supply.