[com.android.chrome] Chrome doesn't log in to existing / new account

Affected app
Name: Chrome
Package id: com.android.chrome
Version: 88 / 89 / 90

Describe the bug
When trying to log into Chrome, it prompts me to sign into a new account instead of logging into an existing account. This happens no matter if I have added a Google account in microG in advance.

To Reproduce
Steps to reproduce the behavior:

1. Log into a Google account in microG
2. Open Chrome's setting page, and click "Sign in to Chrome", then click "Add account"
3. microG's sign in screen shows up
4. "This account is already on your device"

Expected behavior
Clicking "Sign in to Chrome" should sign me in directly.

Screenshots
No

System
Android Version: 8.1 / 11.0
Custom ROM: LineageOS 15.1 / LineageOS 18.1

microG
microG Core version: 0.2.17 / 0.2.18
microG Self-Check results: All ticked

Additional context
Signing into Chrome used to work on the same device with the same rom, and this issue appeared somewhere around Chrome 87.
I don't know if this matters but on LineageOS 15.1, the signature spoofing feature was enabled by the Nanodroid patcher.

Start by reproducing the flow from Chrome settings: choose “Sign in to Chrome,” select “Add account,” and observe microG’s sign-in screen reporting that the account is already on the device. Compare this behavior across the listed Android, Chrome, and microG versions; done means an existing Google account can sign in to Chrome without being prompted to add it again.