No no pairs are good, using a ram without its store bought pair is bad. I don't know enough about ASRock boards to give a specific answer but Ram that's sold in pairs generally doesn't work as well individually because modern boards apparently divide work between them in specific ways.

I need to read about how our boards (mine's b550m) work regarding that but I'll dm you whatever I find

Just decided to reply in case anyone else doesn't know. Tom's Hardware and a few different mb manufacturer websites say motherboards opt for Dual Channel ram management, if you have an uneven number it will still use them all on a single channel mode which is slower but not as badly as if you had mixed RAM parts