Discord.js member.timeout is not a function

I try to make a /timeout discord command and therefore need a GuildMember instead of a User, but discord only allows Users to be an option in a slash command so I can’t directly ask for a member. So I have the user and use guild.members.fetch({target, force: true}) to fetch him from the guild members. Afterwards I check if member != null to make sure the member exists (= is in the guild).
At the end I call member.timeout(durationInMs, `${reason} | Von ${interaction.user.username}`); to timeout the member, but I get TypeError: member.timeout is not a function.
Full code:

const { SlashCommandBuilder, EmbedBuilder, Colors, PermissionFlagsBits } = require('discord.js');
const ms = require('ms');

module.exports = {
    data: new SlashCommandBuilder()
        .setName('timeout')
        .setDescription('Versetze einen Nutzer für eine bestimmte Zeit in den Timeout')
        .addUserOption(option =>
            option.setName('target')
                .setDescription('Der Nutzer, den du timeouten möchtest')
                .setRequired(true))
        .addStringOption(option =>
            option.setName('duration')
                .setDescription('Die Dauer (bspw. 30m für 30 Minuten oder 2h für 2 Stunden), nach der der Timeout aufgehoben wird')
                .setRequired(true))
        .addStringOption(option =>
            option.setName('reason')
                .setDescription('Der Grund, aus dem du den Nutzer timeouten möchtest'))
        .setDefaultMemberPermissions(PermissionFlagsBits.BanMembers),
    async execute(interaction) {
        const {guild} = interaction;
        const target = interaction.options.getUser('target');
        const member = guild.members.fetch({target, force: true});
        const reason = interaction.options.getString('reason') ?? 'Kein Grund angegeben';
        const duration = interaction.options.getString('duration');
        const durationInMs = ms(duration);


        if(member == null){
            const embed = new EmbedBuilder()
                .setColor(Colors.Red)
                .setTitle('Aktion')
                .addFields(
                    { name: '<:scroll:1133359100252651591> Ergebnis', value: 'Fehlschlag', inline: true },
                    { name: '\u200B', value: '\u200B', inline:true},
                    { name: '<:info:1133359642664251492> Aktion', value: 'Timeout', inline: true },
                    { name: '<:clipboard:1133357741394645084> Nachricht', value: `Der Nutzer ist nicht Teil dieses Servers.`, inline: true },
                )
                .setTimestamp();
            await interaction.reply({embeds: });
            return;
        }

        if(durationInMs == null){
            const embed = new EmbedBuilder()
                .setColor(Colors.Red)
                .setTitle('Aktion')
                .addFields(
                    { name: '<:scroll:1133359100252651591> Ergebnis', value: 'Fehlschlag', inline: true },
                    { name: '\u200B', value: '\u200B', inline:true},
                    { name: '<:info:1133359642664251492> Aktion', value: 'Timeout', inline: true },
                    { name: '<:clipboard:1133357741394645084> Nachricht', value: `Die angegebene Dauer ist falsch.`, inline: true },
                )
                .setTimestamp();
            await interaction.reply({embeds: });
            return;
        }

        if(durationInMs > 2419200000 ){
            const embed = new EmbedBuilder()
                .setColor(Colors.Red)
                .setTitle('Aktion')
                .addFields(
                    { name: '<:scroll:1133359100252651591> Ergebnis', value: 'Fehlschlag', inline: true },
                    { name: '\u200B', value: '\u200B', inline:true},
                    { name: '<:info:1133359642664251492> Aktion', value: 'Timeout', inline: true },
                    { name: '<:clipboard:1133357741394645084> Nachricht', value: `Die Dauer darf 28 Tage nicht überschreiten.`, inline: true },
                )
                .setTimestamp();
            await interaction.reply({embeds: });
            return;
        }

        if(durationInMs < 1000){
            const embed = new EmbedBuilder()
                .setColor(Colors.Red)
                .setTitle('Aktion')
                .addFields(
                    { name: '<:scroll:1133359100252651591> Ergebnis', value: 'Fehlschlag', inline: true },
                    { name: '\u200B', value: '\u200B', inline:true},
                    { name: '<:info:1133359642664251492> Aktion', value: 'Timeout', inline: true },
                    { name: '<:clipboard:1133357741394645084> Nachricht', value: `Die Dauer darf eine Sekunde nicht unterschreiten.`, inline: true },
                )
                .setTimestamp();
            await interaction.reply({embeds: });
            return;
        }

        const formattedDuration = ms(durationInMs);

        const embed = new EmbedBuilder()
            .setColor(Colors.DarkRed)
            .setTitle('Aktion')
            .addFields(
                { name: '<:scroll:1133359100252651591> Ergebnis', value: 'Erfolg', inline: true },
                { name: '\u200B', value: '\u200B', inline:true},
                { name: '<:info:1133359642664251492> Aktion', value: 'Timeout', inline: true },
                { name: '<:clipboard:1133357741394645084> Grund', value: `${reason}`, inline: true },
                { name: '\u200B', value: '\u200B', inline:true},
                { name: '<:moderator:1133359611852886047> Moderator', value: `${interaction.user}`, inline: true },
                { name: '\u200B', value: '\u200B', inline:true},
                { name: ':alarm_clock: Dauer', value: `${formattedDuration}`, inline: true },
                { name: '<:check:1133357168993783910> Ausgeführt gegen', value: `ㅤㅤ<:arrow:1133359137091227648> ${target}`, inline: false },
            )
            .setTimestamp();
        await interaction.reply({embeds: });
        member.timeout(durationInMs, `${reason} | Von ${interaction.user.username}`);
    },
};

>Solution :

Did you try to await your member from your guild ?

const member = await guild.members.fetch({target, force: true});