With Monterey 12.7.6 released over a year and a half ago, what you are experiencing is not something that was caused by Apple in that release, so it will not be solved by them. You may certainly be having a network connection issue where you are seeing low speeds. This would be more due to your router, ISP or even your email provider.
Third party software installed on your computer may also have an effect on network speeds. It is possible that providing the EtreCheck report may be used to identity any problematic software. Common ones that would do that are VPN's, AntiVirus, or Cleaner apps.
How to use the Add Text Feature When Post… - Apple Community
Another thing you can try is starting in Safe Mode as a test. Note that it will take quite a bit of time to start up in Safe Mode, and to exit you just need to start up normally again.
Start up your Mac in safe mode - Apple Support (IN)