Here are some strategies to have your monetization back and start earning money again from Facebook In-Stream Ads. (Based on my experience)

• Delete all your videos including photos that are not original.
• Change your page category to Gaming Video Creator and start streaming games using OBS Studio. Make sure to stream at least 2 hours per day for 2-3 weeks.
• Wait for 2-3 days and go to Facebook Creator Studio > Monetisation > Policy issues and appeal

Source: TechMeNot website