After latest update my fairphone 5 has problems taking charge especially when the battery is drained. First occasion the phon continuously tried to restart several times until a different symbol we’d a drained battery and a blinking socket plug cam up. Left it over night next morning it was back to normal. Now the second time the battery indicator just stays at 1%.
Looks like you are using a charger lacking enough power to charge and start the phone at the same time.
Or the cable or socket has contact problems. Try to use a charger with more power or a different cable. Check the socket whether there is debris in it, preventing the cable from having full and secure contact.