Joycons have input lag or stop responding to Switch (even new ones)

Background: I’ve had my Switch for 2 years and have played Smash Ultimate since it came out. After a couple of months playing Ultimate (~May 2019), my Joycons started experiencing Joycon drift and would sometimes not do what I told them to do, so I bought new ones. The new Joycons worked fine (no drift) but after a month, they would again sometimes have severe input delay or not do what I told it to do. Whenever I noticed it happening, I would have to stop playing that day and it’d usually be fine the next day. I sent them in for repair to Nintendo and they worked fine for about 2 weeks before it started doing the same thing again.

It got really bad recently, so I bought a third pair of Joycons. Today was my first day playing with them and it started happening again.

Some more facts:

• I have never dropped my Switch or Joycons
• I play with the Joycons disconnected from the console (usually docked) no more than 5 feet away from the screen. It still happens when I play 6 inches away from the screen (this only happens when I play it undocked).
• I’ve played at home and my college dorm (different TV’s). Both have very strong internet connections, although this problem happens even when I don’t play online.
• Sometimes I’ll notice the Joycon start losing connection after a “strong hit” (such as a move in Smash Ultimate that causes a heavy rumble), like something was knocked loose in the controller (not literally). Once I feel it start to happen, it progressively gets worse and worse (the vibration becomes even more and more “hollow” until it’s borderline unplayable).
• There are no devices near the Switch/TV that use Wifi (no microwave either) that can interfere with the signal.

Here’s what I’ve tried to resolve this:

• Bought new Joycons (didn’t solve it)
• Tried different channels on my WiFi (I use 5ghz) (didn’t solve it)
• Sent previous Joycons in for repair (didn’t solve it)

The best analogy I can think of for what I’m experiencing is if you're driving and you run over a bad pothole/rock and you feel like something went wrong with your car and it gets worse until you get the car checked out.

I am quite convinced it is a connection issue with the Switch and not a controller issue (since the brand new Joycons also had issues), but have no idea how to go about troubleshooting that. I wish I could find a Nintendo person to contact and ask about my situation but any “controller not responding correctly” only leads to getting Joycons repair. Thanks for any help you can offer!