It's all about which cable you get. Or, more specifically, the chip inside the cable.

The majority of cheap cables use a super low-cost chip that ruins data at higher baud rates.

If you get a quality cable with a known good chip in it, then you can transmit at crazy speeds.

My TRS-80 is supposed to max out at 300 baud. But I can go to 600 baud with a crap cable, or 57,600 with a good cable.

If we are talking about original arduino uno, as in https://www.pololu.com/product/2191, then cable should not matter - the converter is on the board, the cable is dumb.

The knock-off often use ch340 chip (which is super annoying as it has no serial number of any sort), but even that chip can be pretty fast if placed on the well designed PCB - I regularly upload 1MB firmware files to esp8266 at 230400 using that chip.