Note: Season 1 to 4 (all 170 episodes) is fully released and finished since 2021. Nothing missing.
Then they divided them like this
Section 1 = Season 1 (1-51)
Section 2 = Season 2 (52-102)
Section 3 = Season 3 (103-154)
Section 4 = Season 4 (155-170)
So if you've already watched those 4 sections, then you are DONE with the old anime. You are fully caught up!
That "Season 5 with 5 episodes" is the new continuation that just started last month. It's not finished - they are releasing 1 episode every week.