This was the same for me, even though I don't auto login. I was not unduly troubled by it as I used firefox but a couple of months ago I switched to using Brave ( a chromium base browser) and started getting the keyring popups. I did the same thing blanked the password and bingo.whenever I booted this OS from a computer-off state the keyring was NOT unlocked automatically by my logging in.
I believe I have got around the problem by changing my keyring password to blank
I am guessing chromium is protecting the passwords it offers to save for you in those keyrings. And as I dont let it do that ( I use lastPass ) I dont have any security issues by not password protecting the keyring ....unless someone can tell me otherwise?