I finally found a quick and easy solution for this. Use the shopify app "Simprosys Google Shopping Feed" and it has a checkbox to exclude variants when sync'ing your feed. Super easy to use. It does cost $4.99 a month but its worth it if it just gets...

I have started to see some improvements, though it is not back to the levels we were use to. It was a PITA to switch everything over and clear a lot of the errors but I have around 600 products with a lot of variants. It should be less time consuming...

I noticed the same thing with my store starting on March 15th. I definitely think it has something to do with GA4. I have since switched everything over. Hoping that I see a correction in the next couple of weeks!