I could get around similar problem this way:

#!/bin/bash

tmp=$(mktemp --tmpdir=/tmp/).tmux

cleanup () {
        rm -f "$tmp"
}
trap cleanup EXIT

dump_cmd () {
        local i=$1
        shift
        echo "tcpdump -i $i -s 1500 \"port 67 or port 68\" -e $@"
}

cat <<-EOT > "$tmp"
        new-window
        send-keys '$(dump_cmd eno1)' Enter
        splitw -v -p 50
        send-keys '$(dump_cmd enp12s0f2)' Enter
EOT

tmux new 'tmux move-window -t 99 \; source-file '"$tmp"

# EOF #

This script starts two sniffers on two interfaces in two panes.

I could get around similar problem this way:

#!/bin/bash

tmp=$(mktemp --tmpdir=/tmp/).tmux

cleanup () {
        rm -f "$tmp"
}
trap cleanup EXIT

dump_cmd () {
        local i=$1
        shift
        echo "tcpdump -i $i -s 1500 \"port 67 or port 68\" -e $@"
}

cat <<-EOT > "$tmp"
        new-window
        send-keys '$(dump_cmd eno1)' Enter
        splitw -v -p 50
        send-keys '$(dump_cmd enp12s0f2)' Enter
EOT

tmux new 'tmux move-window -t 99 \; source-file '"$tmp"

# EOF #

This script starts two sniffers on two interfaces in two panes.

P.S.

One may use simply

        new-window '$(dump_cmd eno1)'
        splitw -v -p 50 '$(dump_cmd enp12s0f2)'

instead of those four lines, but ^C to tcpdump will kill that pane too. This may not be what you want.