See https://blog.kamens.us/2021/03/19/update-on-using-displaylink-with-ubuntu-21-04-hirsute-hippo/

hirsute-fix-displaylink.sh

#!/bin/bash -e

# You will probably need to adjust this script if you aren't using
# the generic kernel.

to_install=
to_hold=
pd=/tmp/packages.$$
mkdir $pd

# Get good Mesa packages

while read package arch version; do
    to_hold="$to_hold $package:$arch"
    if [ "$version" == "20.3.4-1" ]; then
        continue
    fi
    deb_name="${package}_20.3.4-1_${arch}.deb"
    echo Downloading $deb_name
    curl --location --silent --output $pd/$deb_name \
         "https://launchpad.net/ubuntu/+archive/primary/+files/$deb_name"
    to_install="$to_install $pd/$deb_name"
done < <(dpkg-query --show --showformat \
         '${Package} ${Architecture} ${Version} ${Source}\n' \
         '*mesa*' '*libgbm1*' |
         awk '$4 == "mesa" {print $1, $2, $3}')

# Get good Kernel packages

while read package arch; do
    to_hold="$to_hold $package:$arch"
    if dpkg-query --show $package:$arch 2>/dev/null |
            grep -q -s '5\.10\.0-14\.15$'
    then
        continue
    fi
    deb_name="${package}_5.10.0-14.15_${arch}.deb"
    echo Downloading $deb_name
    curl --location --silent --output $pd/$deb_name \
         "https://launchpad.net/ubuntu/+archive/primary/+files/$deb_name"
    to_install="$to_install $pd/$deb_name"
done < <(dpkg-query --show --showformat \
         '${Package} ${Architecture} ${Version} ${Source}\n' '*linux*' |
         awk '$4 == "linux" || $4 == "linux-signed" {print $1, $2}' |
         sed 's/-5\.[0-9.]*-[0-9]*/-5.10.0-14/' | sort -u)

# Get good Kernel meta-packages

while read package arch version; do
    to_hold="$to_hold $package:$arch"
    if [ "$version" == "5.10.0.14.16" ]; then
        continue
    fi
    deb_name="${package}_5.10.0.14.16_${arch}.deb"
    echo Downloading $deb_name
    curl --location --silent --output $pd/$deb_name \
         "https://launchpad.net/ubuntu/+archive/primary/+files/$deb_name"
    to_install="$to_install $pd/$deb_name"
done < <(dpkg-query --show --showformat \
         '${Package} ${Architecture} ${Version} ${Source}\n' '*linux*' |
         awk '$4 == "linux-meta" {print $1, $2, $3}')

if [[ $(uname -r) =~ 5\.11 ]]; then
    echo
    echo "*** NOTE NOTE NOTE ***"
    echo
    echo "The following command is going to fail if you already have"
    echo "evdi-dkms installed, because the evdi kernel module will"
    echo "fail to build for kernel 5.11, and this script cannot"
    echo "uninstall the 5.11 kernel because you are currently"
    echo "running it. If that happens, then, after the command fails,"
    echo "you need to reboot, select the 5.10 kernel during the boot"
    echo "process, and then run this script again."
    echo
    echo "*** NOTE NOTE NOTE ***"
    echo
fi
    
if [ -n "$to_install" ]; then
    apt-get install $to_install
fi

if [[ $(uname -r) =~ 5\.11 ]]; then
    echo
    echo "*** NOTE NOTE NOTE ***"
    echo
    echo "You need to reboot, select the 5.10 kernel during boot, and"
    echo "rerun this script."
    echo
    echo "Before rebooting, make sure GRUB_TIMEOUT is set to a non-zero value"
    echo "and GRUB_TIMEOUT_STYLE is set to 'menu' in /etc/default/grub, and if"
    echo "you have to change either of them, run 'sudo update-grub' before"
    echo "rebooting. Otherwise, you won't be able to easily select the 5.10"
    echo "kernel when you reboot."
    echo
    echo "*** NOTE NOTE NOTE ***"
    echo
    exit 1
fi

apt-mark hold $to_hold

# Uninstalling the 5.11 kernel

to_remove="$(dpkg-query --show --showformat \
         '${Package} ${Architecture} ${Version} ${Source}\n' '*linux*' |
         awk '$4 == "linux" && $3 ~ /^5\.11/ {print $1 ":" $2}')"
apt-get remove $to_remove

rm -rf $pd