elevation showing small spikes in the second half of my run

Hi,

For the last few weeks, my garmin fenix 5 is showing tiny spikes in my elevation in the second half of my run.  It will be ok and then about half way, it starts to show tiny spikes that over inflate the elevation.  I've attached an image showing it.

I believe my software is 25.00 and this was synced on garmin express before these runs.

Any ideas?