Campaign fails to process

I upgraded to version 3.6.14 before realizing that I needed PHP 8.0. I have since deleted 3.6.14 and reinstalled 3.6.12 under PHP version 7.4.

Exported subscribers from 3.6.14 db (csv) and imported them into 3.6.12 db

Created a list called test with 2 subscribers and tried sending a campaign. Keep getting “queue fail to process.” When accessing the database (MySql) I get an error message that reads: “Database error 1226 while doing query User ‘xxx’ has exceeded the ‘max_questions’ resource (current value: 150000)”

Also, when creating a campaign, save and continue editing, and try sending a test message to me, I get no response and no email.

How do I resolve these two problems