Something wrong with relations

Start with App.js and the HydraAdmin relation form for ProposalParam, then inspect the network request generated when selecting ProposalType. Compare the field metadata with the entity relation and API response; the issue is resolved when the ManyToOne field submits a ProposalType IRI rather than a nested array.

PHP: 8.2
Symfony: ^6
Api platform: ^3.2
Admin api platform: ^3.4.4

I created entity ProposalType.php

#[ORM\OneToMany(mappedBy: 'proposalType', targetEntity: ProposalParam::class)]
private Collection $proposalParams;

    public function __construct()
    {
        $this->proposalParams = new ArrayCollection();
    }

    public function getProposalParams(): Collection
    {
        return $this->proposalParams;
    }

    public function addProposalParam(ProposalParam $proposalParam): static
    {
        if (!$this->proposalParams->contains($proposalParam)) {
            $this->proposalParams->add($proposalParam);
            $proposalParam->setProposalType($this);
        }

        return $this;
    }

    public function removeProposalParam(ProposalParam $proposalParam): static
    {
        if ($this->proposalParams->removeElement($proposalParam)) {
            // set the owning side to null (unless already changed)
            if ($proposalParam->getProposalType() === $this) {
                $proposalParam->setProposalType(null);
            }
        }

        return $this;
    }

And another entity ProposalParam.php

    #[ORM\ManyToOne(inversedBy: 'proposalParams')]
    #[ORM\JoinColumn(nullable: false)]
    private ?ProposalType $proposalType = null;
    
    public function getProposalType(): ?ProposalType
    {
        return $this->proposalType;
    }

    public function setProposalType(?ProposalType $proposalType): static
    {
        $this->proposalType = $proposalType;

        return $this;
    }

This is pretty simple ManyToOne relation. Generated by make:entity. I'm dont modified this.
Wanted that ProposalParam entity has ProposalType entity by relation, it is simple.

I can create ProposalType via api platform with POST request to /api/proposal_types. And it is successfull.
Then i can set this ProposalType in ProposalParam via POST request to /api/proposal_types. And it is successfull.
Records are inside database and set up like needed.

When i go to admin panel and send request to create ProposalParam i can set ProposalType.

But request sends as array

And error occured Nested documents for attribute "proposalType" are not allowed. Use IRIs instead.
And this is expected, we send array, but api wants IRI.

App.js in admin pretty standart, do not modify something

import { HydraAdmin } from "@api-platform/admin";

export default () => (
    <HydraAdmin entrypoint="http://localhost:9191/api" />
);

Main goal is why system generate select where i need to specify array of ProposalTypes, instead of one ProposalType. Can someone help with it?