Slow downloading emails

You have presumably enabled Mail Privacy Protection:

If you see 'Unable to load remote content privately' at the top of an email - Apple Support

As a diagnostic exercise, disable this feature - then force-restart your iPad:

Settings > Mail > Privacy Protection > Protect Mail Activity - set to OFF

Force-restart:

• On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
• On other iPad models: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.

After restarting your iPad, test your email and note any improvement to performance.

I have several googlemail accounts and a btinternet account which download just as rapidly as they always have. However, my main googlemail account downloads the emails very slowly onto all Apple devices - MacBook Pro and Air, iPads and iPhones. Signing in to the account in Safari does not have any of these problems.

I have force quit and cleared cache on an iPhone, updated all devices to latest software (MONTEREY 12.5 & IOS 15.6), uninstalled and reinstalled the account from Mail and got no help from googlemail - I had 12.5 Gb stored in 15Gb of storage which I had paid to increase to 100Gb.

THIS PREDATES THE "UNABLE TO LOAD REMOTE CONTENT PRIVATELY" ISSUE