My guess it just doesn’t evict stuff from before the suspend, starts re-loading stuff after the resume, which makes the apparent amount “used” go up.
On a normal linux system, “free” RAM will over time drop down to zero, as the kernel puts the extra memory available to use. But it doesn’t mean there isn’t room to evict less-needed stuff if necessary.
AFAIK linux only starts actively evicting RAM once it fills up.
Like the other guy mentioned, drill down and see if you can find the actual program causing the problem.
What communities are you frequenting?
The ones I sub and post to have been nice.