Nano production module: Micro SD card not working at full speed

Analog to here I discovered that at SD-card added to the slot of a Nano production based carrier board (Auvidea JN30B, Jetpack 32.3.1) is running only at ultra high speed (~85MB/s) after first boot. After a soft reboot the speed falls back to just high speed (~20MB/sec).
Thetegra210-porg-p3448-common.dtsi in the source looks like:

sdhci@700b0400 { /* SDMMC3 for SD card on NANO */
                status = "okay";
                mmc-ocr-mask = <3>;
                uhs-mask = <0x0>;
                //max-clk-limit = <400000>;
                tap-delay = <3>;

This file was compiled and flash to the device as described here.
After first boot:

sudo cat /sys/kernel/debug/mmc1/ios
clock:          204000000 Hz
vdd:            21 (3.3 ~ 3.4 V)
bus mode:       2 (push-pull)
chip select:    0 (don't care)
power mode:     2 (on)
bus width:      2 (4 bits)
timing spec:    6 (sd uhs SDR104)
signal voltage: 1 (1.80 V)
driver type:    0 (driver type B)

After reboot

sudo cat /sys/kernel/debug/mmc1/ios
clock:          50000000 Hz
vdd:            21 (3.3 ~ 3.4 V)
bus mode:       2 (push-pull)
chip select:    0 (don't care)
power mode:     2 (on)
bus width:      2 (4 bits)
timing spec:    2 (sd high-speed)
signal voltage: 0 (3.30 V)
driver type:    0 (driver type B)

An upgrade to a newer Jetpack Version is currently not possible (due to dependencies to our rootfs).
What could I try to get the sd card to working at uhs speed after reboot?

The 32.3.1 version is too old. Suggest to upgrade version.

Or try this patch.

Thank you for your help. After applying the patch, the sd card is detected as a uhs device even after a reboot.
Sadly now while doing some read- and write-tests on the sd-card, the device seems to completely reset itself.

Any idea what could be the issue that my device is restarting if a lot of reads and writes happen to the sd-card. (They only occurre after first soft reboot)

sorry. Really no idea about it especially you are using a very old software.

The latest version supported by Auvidea for the used device is NVIDIA L4T 32.6.1. In addition to a working sd card we need to disable the spread spectrum (like here).
How do I disable that on 32.6.1 for a Jetson Nano Production?