Season 4 starts with episode 64, which aired in Japan on October 11, 2019.
The most recent additions will have an '*' by them.
Episode 67 Episode 68 Episode 69
Episode 83 Episode 85 Episode 86
Episode 88 marks the end of the 4th season, but good News again! To be continued 5th Season. As usual, I'll be keeping up by reading the manga!