its not the browser default you need to change, but the email client you use

go to phone's settings>apps>email app>clear defaults

 

Also, Chrome is an insidious POS.
You already stated that you know it works poorly.

What you need is a browser that uses Android System Webview.
Chrome sometimes acts as a webview, and Firefox uses its own.

That is how Google knows everything you do on your device, and why Firefox is so large (and slow).

Android System Webview is built into all Android devices, and is what allows apps to show web content.

Depending on the device you may need to go into Developers Options and choose Android System Webview as the Webview Implementation.

Some devices force you to disable Chrome for this to be possible.

A browser that uses Android System Webview will most often be mistaken for Chrome by websites, and will be fast.

Also, it will be small.

Here is a browser called Lightning that I have used for years.
There are also a few legitimate varients that have different features (dark mode, etc.).

I would see if any of those sites that demand you use Chrome can be be accessed using Lightning instead.

https://f-droid.org/en/packages/acr.browser.lightning/

https://f-droid.org/en/packages/org.midorinext.android/

https://f-droid.org/en/packages/com.cookiegames.smartcookie/

The default search engine is Google (yuck), but can be set to whatever you like- as can the homepage.

 

When you install another app capable of handling an "intent" (i.e. an action such as handling a link) the system will clear the current default for that intent, since as far as it knows you might want to use the new app instead. That's probably what happened here.

Being the default app for opening an email (or handling a "mailto" link) is not the same as being the default browser or the default webview, it's more specific. So it's possible for one app to be the default browser but another app to be the default for handling email links. I'd have thought that if you went into Settings > Apps, found Chrome and cleared all of its default actions that would undo this, if I am understanding the (since resolved) problem correctly.

(I've never used Chrome as my browser, and always disable it if I can't uninstall it. This is mainly because I've always assumed that the whole point of Chrome was to give Google direct access to people's entire browsing activity, and I never felt inclined to play along with that.)

 

Good thread; thanks for posting.
And thanks for the excellent responses.
I will study the implications.

I am currently stripping my Android 10 M11 Chinese phone down to limit it to my very modest requirements.

1. No mobile internet. - I have it at home on my Linux Mint desktop machines.

2. Stable phone number contacts (this took a while as I was losing numbers - after I turned off Google sync, the problem disappeared).

3. WiFi available if and when required (occasionally).

4. Camera, sound recorder available with one click.

5. Maps available using Waze after data turned back on.

Jim.