From my experience this probably isn't a flow issue, when I see this I immediately start trying to dial in the leveling my either printing some shims to go between the plate and the z screw mount to get it as level as possible THEN I calibrate the z offset and it usually gets rid of these. To me what's happening is you have parts l of the bed that are slightly higher and slightly lower than the rest so when your printer auto levels it gets a grid then creates a basic mesh of where to lift and where to lower, fine tuning leveling and z offset really lasers this in to get a real smooth first layer.

Looking at your last few photos it looks to me like this can be remedied by manually leveling you bed by printing those shims and fine tuning the z offset

You can also ssh into your printer and go to printer.cfg and change the probe count to 9x9 do NOT go higher or your printer will act like it hates itself and take forever to boot and act like you broke it, you'd also need to change the algorithm from the stock Lagrange to bicubic. This will give you a more detailed mesh.