Dear maintainers and people intrested in this bug,
I have tested the kernel of the buster backports:
~$ uname -rm
5.4.0-0.bpo.3-686-pae i686
And hibernation including resuming works fine with it.
Best regards
EinSteiGer
~$ uname -rm
5.4.0-0.bpo.3-686-pae i686