Google Docs issue: Copy/paste messing up table lines

Hey there,
I’ve been using Google Docs for a few years now—on my phone, my desktop, and my laptop—but over the last couple of weeks, things have gone totally sideways. Every time I try to copy and paste from one table into another on my laptop, even when the formatting is identical, all the vertical lines just vanish in the destination table, leaving me with nothing but horizontal ones.
I’ve tried messing around with the various "paste special" options, but honestly, none of them work; it’s like the paste command doesn't even register, so I just end up hitting "ctrl+z," which then wipes out the existing table lines that I now have to manually fix.
The weird thing is, I don't run into this at all on my phone, so I'm completely stumped as to why this is happening.

On top of that, even before this mess started, I noticed that sometimes the formatting I’m pasting—like centered text or word wrapping—just gets ignored, even though both tables are set up exactly the same way. It doesn't happen every single time, just randomly...

So, if anyone actually knows what the hell is going on here, please help a person out.

Ever tried opening this in Edge, Chrome, Opera, or whatever else... see if it still acts up.

I gave it a shot in Google Chrome, and honestly, it’s the exact same mess.
But for some reason, everything works perfectly fine over in Microsoft Edge.
🤔
So, is this just some weird setting buried deep within Mozilla that I've messed up? Is there any way to actually figure out what's going on, or am I just stuck forced to use Edge from now on?