BL42, aww, I feel you. The year COVID shut down schools, I encountered a similar loss--I temporarily stopped seeing my kids daily, something I had previously been accustomed to. If this new schedule gives you less than 50/50, or your Right of First Refusal terms are written just right, you may have recourse. I'll leave that to your lawyer who knows your state and agreement.
Assuming you still have 50/50 and Right Of First Refusal does not apply--I assume her parents are not "bad" for your kids and this is mostly about your feelings. Which are important. During COVID I began calling my kids more during my ex's custody time. Is that a possibility? My ex actually had no issues with that and we've shifted much more to a co-parenting mood over the last couple of years.