GA Import overwriting Matomo visitor data

Around 2 weeks ago I kicked off the import for several years of GA data, and I switched the tracking for my website over to Matomo on the same day, logging against the same site ID that the import created. The logging was coming through perfectly, however since the GA import caught up with the new data, the Visits Over Time graph has been overwritten with the data from GA which shows 0 visits per day.

I can still see the original data in the visit log. Is there any way to reprocess the data for that graph to remove the GA data after the switchover date?

For all reports:
Maybe you can try this?