calendar event email notifications popping up on iphone

Here is the problem:

I have certain events on my Google calendar set up with email reminders, not pop up alerts, because these events are not that time critical. Everything always worked as it should in the past but very recently I noticed I'm getting pop up alerts on my iPhone in addition to email reminders. I double checked my Google calendar and the events are only set up for email notifications. But on my iPhone iOS calendar they are just set up for 'alerts' because under event details there is no option for email reminders nor any other reminder besides just 'alert'. So I assume when iOS calendar syncs with my Google calendar, it just reinterprets 'email reminder' as 'alert'. But in the past this has never been the case--I wouldn't receive alerts on my phone for 'email reminder'-only events. It's very annoying to receive pop up alerts on my phone for things that don't actually need my attention.

There was one recent change in my setup that may be causing this, and that was switching from Exchange to CalDav (because Exchange is not supported by Google anymore). But despite my strong suspicion that CalDav is the culprit, I don't know what can be done about it. Any thoughts out there?