My Discord-Bot stopped executing its commands

Just today I've realized that my bot didn't do anything after a new user joined, even though he is supposed to automatically assign a role as he did before. After a quick check, he doesn't respond to any commands at all anymore, even though it worked just fine yesterday.

My Bot still connects to the server and changes to the main function still get recognized (as for example changing its online-status oder activity), but the EventListeners don't seem to react and thus, no commands are executed.

The Bot is coded in Java and uses jdk 13, the library used is the net.dv8tion library JDA-4.2.0-175-withDependencies.jar

Things I have already tried which didn't work:

• Let the bot rejoin
• Refresh the bot and try a refreshed Token
• Update Java
• Assign Administrator-Permissions (again)
• Use the create()-command instead of the JDABuilder (maybe I did it wrong)

Also, I have to point out that other Bots, as for example the Rythm-Bot on our server, run completely fine.

Here are some screenshots that may give the information you need (code snippets & discord example)

https://i.stack.imgur.com/DYS1B.jpg

I am "fairly new" to coding, so even if you have to criticize some snippets shown, I will happily implement upgrades or cleaner code, but the main priority is to get this bot running again. I hope you can help!

Edit: code snippet as text

    public class Main {
    public static JDA jda;
    public static String prefix = "rev";
    public static String adminPrefix = "toolkit";


    public static void main(String[] args) throws LoginException {
        jda = new JDABuilder(AccountType.BOT).setToken("my bot token").build();
        jda.getPresence().setStatus(OnlineStatus.IDLE);
        jda.getPresence().setActivity(Activity.playing("mit nem Butterfly"));
        jda.addEventListener(new commands());
        jda.addEventListener(new serverJoin());
        jda.addEventListener(new adminCommands());
        jda.addEventListener(new selfRoles());
        jda.addEventListener(new chatlog());
        jda.addEventListener(new selfRoleRemove());
    }
}

example class: joining the server

public class serverJoin extends ListenerAdapter {


    public void onGuildMemberJoin(GuildMemberJoinEvent event) {
        Guild guild = event.getGuild();
        Role role = guild.getRoleById(736342426632847381L); //initialisiert die oben eingegebe Rolle
        Member member = event.getMember(); //sucht, wer gejoined ist
        assert role != null;
        guild.addRoleToMember(member, role).complete(); //vergibt die Rolle
        String[] nachrichten = {
                "[member] hat sich auf diesen Discord verirrt, warmen Empfang bitte!",
                "Macht gefälligst Platz für [member]!",
                "Willkommen bei Reveries, [member]",
                "Hey [member], schönen Aufenthalt!",
                "Räumt gefälligst auf, wir wollen keinen schlechten Eindruck gegenüber [member] machen!",
        };
        Random zufallsZahlMacher = new Random();
        int zufallsZahl = zufallsZahlMacher.nextInt(nachrichten.length); //zufällige Textlinie von String[] nachrichten

        EmbedBuilder information = new EmbedBuilder();
        information.setColor(0x00ffff);
        information.setDescription(nachrichten[zufallsZahl].replace("[member]", member.getAsMention()));
        information.setFooter("Willkommen! " + event.getMember().getUser().getName(), event.getMember().getUser().getAvatarUrl());
        event.getGuild().getTextChannelById(753546835347374171L).sendMessage(information.build()).queue();

        event.getUser().openPrivateChannel().flatMap(privateChannel -> privateChannel.sendMessage("**Willkommen auf dem Revery-Discord!** \n Damit du einen guten Start auf dem Server hast, bitten wir dich, die Regeln zu lesen und eine kurze Vorstellung in den #vorstellrunde-Channel zu schreiben. \n Nachdem du deine Vorstellung geschrieben hast (*welche mind. Name, Alter, Hobbies, Musikrichtung und Lieblingsspiel beeinhaltet*), wird dich zeitnah ein Serverteam-Mitglied freischalten und du kriegst Zugang zu unserem Server. \n Damit ein guter Start gewährleistet ist, bitten wir dich, den Command revhelp in den #bot-commands-Channel zu schreiben. \n \n \uD835\uDC16\uD835\uDC22\uD835\uDC2B \uD835\uDC1F\uD835\uDC2B\uD835\uDC1E\uD835\uDC2E\uD835\uDC1E\uD835\uDC27 \uD835\uDC2E\uD835\uDC27\uD835\uDC2C \uD835\uDC1A\uD835\uDC2E\uD835\uDC1F \uD835\uDC1D\uD835\uDC22\uD835\uDC1C\uD835\uDC21!")).queue();
        }
    }

The JDABuilder constructor new JDABuilder(..) has been deprecated since june. You should be using JDABuilder.createDefault(token) instead. To use onGuildMemberJoin the documentation also tells you that GatewayIntent.GUILD_MEMBERS is required. Enable this on your JDABuilder with enableIntents.