Outside some swapiness tutorials I've got nothing I can really share. I typically have the opposite issue where I have gobs of free RAM that's ignored while the swap file is like a prime time New York subway car (crammed full to the nuts).
Given my work laptop has half the RAM your machine does (it's OLD and lacks the problem I mentioned about Gobs-O-RAM heh) and I don't have those issues (but I don't run KDE for this reason) I'd play around with a few things.
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Disable the ZRAM-generator in the Garuda-Assistant so things have to write to disk rather than RAM.
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Open your browsers task manager and see if a specific webpage or extension is being a pig (or has a memory leak). Normally the browser task manager can be opened by right clicking in the tab bar where there are no tabs. This can be tricky if you have a small screen so you might need to open it with only one of your normal tabs open then open the rest after. Then go about your business and when things get bad you have it open to see if anything has gone nuts.
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Try a different browser. Discord can be a pig and perhaps Firefox is just caching too much crap. (Just don't add Chome to the list of browsers to try and see next point)
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Disable Firefox cache. Just don't let it save anything outside immediate working memory.
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Disable all the fancy crap in KDE (you're on an IGP/APU so system memory is video memory i.e. all those fancy shadows/wobbles, transparency, fade in's and slide outs may be adding to the problem)