And since you won’t be able to modify web pages, it will also mean the end of customization, either for looks (ie. DarkReader, Stylus), conveniance (ie. Tampermonkey) or accessibility.
The community feedback is… interesting to say the least.
You can take it a step further and include a please note my email address has changed in your signature
Email has a special header for this called “Reply-To” which is respected by pretty much every client. When anyone replies to your mail they won’t even realize it’s to another address than they received the mail from.
Also you don’t need to keep it for search history. Download all your mail with imap to some proper mail client and you can move it to a new provider if you really want to.