OP why do you want to fix this? Are you worried about language development? Not understanding what he wants? Want him to be more polite/less annoying?

I think the goal will affect how you should approach it.

Normal! But definitely a good time to say:

"If you want a banana say: Banana please" or whatever.

They're very teachable right now even though they might fight it. If he wants things he'll learn fast.

Perfectly normal.

Totally normal, especially when they’re tired/hungry/otherwise cranky. New skills are hard! You can say “words please” or “use your words” but I mostly only did that if I didn’t think it would turn into a power struggle or I genuinely didn’t understand what was wanted.

How do I encourage my 22 month old to use his words when he wants something? I know he is capable of it but often lately he’s been whining and gesturing. Could this be a regression? Or just a regular cranky phase (think he’s teething)?