I have an AOSP Android 9.0 based ArrowOS ROM in my spare cell phone Zuk Z2 Pro. In my old LG G5 I have LineageOS 16.
Chrome and Instagram work on them just fine and their versions/builds are exactly the same with the ones in my MI 9 SE.
So, I fail to see why this would be a Chrome- (or Instagram-) specific issue and not a MIUI-specific.
You wrote "..Tell that to Xiaomi, the guys you paid for your device, not me. I already do more than enough, I don't need you to give me instructions. "
At your site's About us (down below) you state "Since 2010 our web site has officially worked with Xiaomi on a variety of projects for APP translations and bug fixing and is a major part of today's Xiaomi Global ROM experience thanks to the great team at xiaomi.eu and its community. "
I use XIAOMI.EU ROM in my 9SE and that's why I reported to this forum something that looks like a bug (in ROM) to me. If your co-op with Xiaomi has since developed a more distant nature, you might want to update your 'About us'.
Best regards,
Mr. Jari Jäntti, Finland.