Here is a not so nice thought: These people are not (necessarily) refugees.

I mean that, as defined by the 1967 protocol^1^ (which is mostly just the 1951 conventions^2^ definition, but without the time limitation). Therefore the right to non-refoulment (i.e. not returning a person to their prior country) does not apply to them. The EU has a lesser definition "subsidiary protection"^3^ which these people ~~do~~ might[?] qualify for (as it includes ~~war~~ "serious and individual threat to a civilian’s life or person by reason of indiscriminate violence in situations of international or internal armed conflict"), but as far as I can read, the directive does not define any rights for these people. So the exact things a person under subsidiary protection is afforded is up to the individual country. I am probably missing some "laws", but otherwise there is, legally as far as these "laws" go, nothing wrong, with‒e.g.‒Germany (assuming German law doesn't define non-refoulment for S.P.) returning Ukrainians to Ukraine.

^1^ https://treaties.un.org/Pages/showDetails.aspx?objid=0800000280048bb8&clang=_en
^2^ https://treaties.un.org/Pages/showDetails.aspx?objid=080000028003002e&clang=_en
^3^ https://eur-lex.europa.eu/legal-content/en/TXT/?uri=CELEX%3A32011L0095

Definition as modified by the 1967 protocol:

owing to well-founded fear of being persecuted for reasons of race, religion, nationality, membership of a particular social group or political opinion, is outside the country of his nationality and is unable or, owing to such fear, is unwilling to avail himself of the protection of that country ; or who, not having a nationality and being outside the country of his former habitual residence, is unable or, owing to such fear, is unwilling to return to it