Due to what's likely COVID-19 related production issues, the second season of Mushoku Tensei: Isekai Ittara Honki Dasu has been delayed to the Fall 2021 anime season after being originally slated to begin during the Summer. For reference, anime series debuting in the summer typically start in July while those beginning in the Fall kick off in October.
While COVID-19 pandemic largely appears to be under control in the U.S., Japan is currently suffering from a renewed surge in cases and recently had to extend its state of emergency. There are many pundits who think the Tokyo Olympics (which were already delayed by a year) might be canceled.
The Mushoku Tensei: Jobless Reincarnation TV anime debuted during the Winter 2021 anime season and was something of a surprise hit. The 11-episode first cour had fans eagerly anticipating a second season but they'll have to wait a bit longer.
What separates Mushoko Tensei apart from a plethora of other isekai anime is the fact that its based on 2012 light novel series that largely set the trend for modern isekai tropes. In particular, the light novel popularized the reincarnation aspect of being transported into a new world rather than simply being summoned or teleporting.

Despite being bullied, scorned, and oppressed all of his life, a thirty-four-year-old shut-in still found the resolve to attempt something heroic—only for it to end in a tragic accident. But in a twist of fate, he awakens in another world as Rudeus Greyrat, starting life again as a baby born to two loving parents.
Preserving his memories and knowledge from his previous life, Rudeus quickly adapts to his new environment. With the mind of a grown adult, he starts to display magical talent that exceeds all expectations, honing his skill with the help of a mage named Roxy Migurdia. Rudeus learns swordplay from his father, Paul, and meets Sylphiette, a girl his age who quickly becomes his closest friend.
As Rudeus' second chance at life begins, he tries to make the most of his new opportunity while conquering his traumatic past. And perhaps, one day, he may find the one thing he could not find in his old world—love.