For the Levites left their common lands and their holdings and came to Judah and Jerusalem, because Jeroboam and his sons cast them out from serving as priests of the LORD,
See here, I. How Rehoboam was strengthened by the accession of the priests and Levites, and all the devout and pious Israelites, to him, even all that were true to their God and their religion. 1. Jeroboam cast them off, that is, he set up such a way of worship as he knew they could not in conscience comply with, which obliged them to withdraw...
Commenting on 2 Chronicles 11:13-23
And after them out of all the tribes of Israel,.... Besides the priests and Levites, and after their example, many of the common people, out of all the ten tribes: such as set their hearts to seek the Lord God of Israel; to seek his face and favour, where he was to be found; to worship him according to his revealed will, and to receive...
The Levites left their suburbs - They and the priests were expelled from their offices by Jeroboam, lest they should turn the hearts of the people to the true God, and then they would revolt to Judah, Kg1 12:26; and therefore he established a new worship, and made new gods.