I bought extra RAM for my new iMac 27" Inch however it's made it slower than ever

Hello!

I am new here to posting so hopefully I can explain fully what is wrong and maybe you can help me.

So I have the iMac 27" 5K 2019 and I have only had it around 5 months...

Well I thought that it would be a good idea if I bought some extra RAM as I do a lot of work in Adobe Premiere Pro, Photoshop and After Effects and I noticed sometimes it would lag a little when I would be editing footage so I thought because there are slots in the back extra RAM might help this and I had some money saved so I thought, why not right?

I looked around at deals and I honestly could not afford the prices on the apple website for what they were asking for literally the same RAM which I found on amazon... so I bought this one - https://www.amazon.co.uk/gp/product/B071H38422/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1

I installed it, everything went well... however I noticed ZERO difference.

fast forward 2 months later and the iMac is worse than ever... I can even barely edit anymore because Premiere Pro lags so bad that is virtually impossible to playback footage I am editing, rendering my videos takes twice as long, opening apps now is ridiculous... and often everytime I open an app, even Google Chrome is says "not responding"... I even timed one day and it took me 4 minutes to open Premiere Pro... but then some days it opens in 5 seconds... which REALLY confuses me... what the **** is going on?!

YES I update all of my apps, my iMac is always updated etc, I don't download illegal videos, music etc so I doubt its a virus or anything like that, I just don't know what happened, and I need to work.. it's my job and during this COVID pandemic I can't exactly take my iMac to an Apple store to be looked at..

So my only guess is that the RAM I bought messed up the mac? should I remove it and return it? and buy another one? A different brand? I am really not sure...

Hopefully someone can help me, because I am losing my mind :D ]

Also here is the specs of my iMac :)

Thank you so much,

Natski

[Image Edited by Moderator to Remove Serial Number]