"A335PBGL" are the characters saved in ROM that identify the Pocket Beagle. The latest uboot is far more device tree based, so from
https://gitlab.denx.de/u-boot/u-boot/-/blob/master/arch/arm/dts/am335x-pocketbeagle.dts it loads $this->bbcode_second_pass_code('', 'model = "TI AM335x PocketBeagle";')
So those two lines in each uboot, are just saying that the Pocket Beagle has been recognised as such. Now this shouldn't affect you problem, which is either accessing the SD card, or accessing ext4 partitions on the card. There is a slim chance that the SD card slot is described wrong in the device tree above:
$this->bbcode_second_pass_code('', '&am33xx_pinmux {
mmc0_pins: pinmux-mmc0-pins {
pinctrl-single,pins = <
AM33XX_IOPAD(0x960, PIN_INPUT | MUX_MODE7) /* (C15) spi0_cs1.gpio0[6] */
AM33XX_IOPAD(0x8fc, PIN_INPUT_PULLUP | MUX_MODE0) /* (G16) mmc0_dat0.mmc0_dat0 */
AM33XX_IOPAD(0x8f8, PIN_INPUT_PULLUP | MUX_MODE0) /* (G15) mmc0_dat1.mmc0_dat1 */
AM33XX_IOPAD(0x8f4, PIN_INPUT_PULLUP | MUX_MODE0) /* (F18) mmc0_dat2.mmc0_dat2 */
AM33XX_IOPAD(0x8f0, PIN_INPUT_PULLUP | MUX_MODE0) /* (F17) mmc0_dat3.mmc0_dat3 */
AM33XX_IOPAD(0x904, PIN_INPUT_PULLUP | MUX_MODE0) /* (G18) mmc0_cmd.mmc0_cmd */
AM33XX_IOPAD(0x900, PIN_INPUT_PULLUP | MUX_MODE0) /* (G17) mmc0_clk.mmc0_clk */
AM33XX_IOPAD(0x9a0, PIN_INPUT | MUX_MODE4) /* (B12) mcasp0_aclkr.mmc0_sdwp */
>;
};
};
&mmc1 {
status = "okay";
vmmc-supply = <&vmmcsd_fixed>;
bus-width = <4>;
pinctrl-names = "default";
pinctrl-0 = <&mmc0_pins>;
cd-gpios = <&gpio0 6 GPIO_ACTIVE_LOW>;
};
')
Which as this is taken direct from the linux dts, it should be correct, and uboot should respond correctly. It a bit strange that mmc1 is using mmc0 pins, but hey ...
Planned last night to print how exactly how the partitions and file systems are defined on my PB, then can see if you have anything different. Anyway was distracted, but hopefully tonight will get time ...