2. Their nameservers are unreliable: https://www.reddit.com/r/freenom/comments/vl71se/freenom_ser...

3. Their client area often doesn't work. I can't login right now, and it seems I'm not the only one having issues: https://www.reddit.com/r/freenom/comments/zwh7o8/an_unexpect...

4. Their email address ([email protected]) bounces because it forwards to their CEO's gmail and their SMTP server doesn't have a PTR record set:

    This is the mail system at host smtp06.freenom.net.
    
    I'm sorry to have to inform you that your message could not
    be delivered to one or more recipients. It's attached below.
    
    For further assistance, please send mail to postmaster.
    
    If you do so, please include this problem report. You can
    delete your own text from the attached returned message.

                       The mail system

    <[redacted]@gmail.com> (expanded from <[email protected]>): host
        gmail-smtp-in.l.google.com[142.250.141.26] said: 550-5.7.25 [216.75.58.148]
        The IP address sending this message does not have a 550-5.7.25 PTR record
        setup, or the corresponding forward DNS entry does not 550-5.7.25 point to
        the sending IP. As a policy, Gmail does not accept messages 550-5.7.25 from
        IPs with missing PTR records. Please visit 550-5.7.25
        https://support.google.com/mail/answer/81126#ip-practices for more 550
        5.7.25 information.