Disappeared trash icon for Gmails on Iphone 6s - why?

I've got an Iphone 6s purchased in 2015. Gmails had a trashcan icon at the bottom of them for the first 4 years I had the phone. Then, suddenly earlier this year, there is only an Archive icon, which makes the process of trashing emails a multi-step hassle.

I've seen other answers to this that refer to "Accounts and Passwords" under Settings, but there is no such option under Settings on my phone, nor is there any "Advanced" option in the mail account. I'd sure like to restore that trashcan icon - any ideas?