I come from an analog background as an 80s recording musician working in studios and have used software and plugins for 20 years. I'm absolutely no expert with digital audio but I've been noticing some of the comments in posts here about aliasing.

It's never concerned me until now. Now, I've looked into this briefly and not with as much depth and knowledge as some of you have, and I'm a little confused.

Should I be concerned about aliasing? I've never noticed anything to concern me about my digital audio before.

I did my own tests using plugins that have high aliasing and processed a file with them using no oversampling, and again the same file with oversampling. I couldn't hear any difference.

I ran the files side-by-side and inverted the phase of one of them to hear any differences between the two.
There was a noticeable brightness but no apparent junk or distortion I could hear so, what's happening here?

As far as safeguards against aliasing are concerned, what do I do? I read that placing a low pass filer at 20KHz before any plugins will guarantee that there's no artifacts produced by aliasing, and also using dithering - is it that simple to fix?

Obviously, I use as much oversampling as possible to ensure quality, but running every plugin at x16 oversampling isn't resource-friendly and a CPU hog, so what would you suggest?

I typically record projects at 48KHz, 24-bit, using REAPER to track and Cubase for mixing.

Thanks in advance.