HRV different R-R charts

Hello
I'm curious, what could cause such different HRV graphs of R-R intervals?
These are two different runs.

The first one looks fine, the second one has a lot of false measurements, e.g. because of bad connectivity of a heart rate strap.

I,ve changed HRM strap recently. Is it possible that these false measurements could indicate a heart problem?

I'm not a doctor, but no, I'm pretty sure there's no heart problem behind.

Ok thank you very much for your quick reply