It’s because your nozzle is ever so slightly too low when you’re printing. I’d adjust your Z offset by one click upwards.
Reprint the cube, and see if that resolved it. If not adjust upwards by another click.
If after a handful of times you can’t get a decent ironing pass, I’d take a look at your extrusion multiplier. Drop it down by 0.01 and recalibrate and retry doing the above ironing calibration sequence again.
Are you really going to interact with the ads though? If you’re going there to cause discord you’re not going to see an ad and go “Oh! Cool I’ve been meaning to try thing that’s as close to a scam as legally allowed” or it literally is just an outright grift. Plus because of that the percentage of interactions on the ads is going to drop hard, meaning now Reddit is a worse place to stick your ads because there’s not a lot of engagement with them.
Yes that drive should work, as long as it’s not a SATA M.2 SSD it should be compatible with the Yellow.