use the question tag to ask for help 🙃

Please, say properly what the issue is. If you're suggesting that your code passes even though it shouldn't, the reason for that is you using a cheat (and one which may lead you to a ban).

However, the key should be increased by 1 with every word in a phrase.

Not a kata issue.

test.assert_equals(caesar_encode("alea iacta est", 3), "dohd megxe jxy")

incorrect testing(e.g. i !-> m with the key of 3)

Then please accept my apologies :-) I am kind of new here...

Correct. Maybe BASIC TESTS in 'attempt' mode has more tests than you see in 'test' mode.

Are you saying that the BASIC TESTS when pressing Attemp is not the same as the BASIC TESTS you get when you click Test?

Nothing broken. When you press "Attempt" there are many more tests.

This one seems broken, when I enter my solution and press Test, it passes the basic tests, but when I press Attempt it fails ON THE BASIC TESTS, that it just passed.

When you post an issue you imply that something is wrong in the kata tests. Instead you can post a question and see if somebody answer.
Maybe you shoud read https://github.com/codewars/codewars.com/wiki/Troubleshooting-your-solution.

i didnt say that something is wrong with the kata. im just wondering whats wrong with my code thats all

There is no error in the tests.
Please before posting an issue look at the top of the page to see how many people passed the kata (14593 with Python); if there were errors somebody would already have seen them.
Print the input to see what happens.