With Netflix you can only watch the 5th season of Spongebob, doesn't another season come sometime?
Netflix doesn't announce anything like that. Sometimes licenses expire and seasons disappear.
e.g. Gravity Falls was removed due to Disney +
One of my favorite Netflix Japan shows: Dragon Ball (153 episodes) and Dragon Ball Z (291 episodes) were removed on May 24, 2020 …
It is not clear whether seasons will continue to appear.