What could be causing STP compatibility mode flapping in Dell OS10

Hey everyone, we have a pair of Dell S-5212FON switches that keep flapping between STP and RSTP on a port-channel. They are both getting flooded with logs saying “%STP_COMPATIBILITY_MODE: STP:Compatibility mode change received for interface port-channel1.Interface operating mode is STP/RSTP for vlan 1.” I ran the command “show spanning-tree compatibility mode” and all of the other interfaces are running RSTP. For the port-channel, all of the VLANs except one are running plan 802.1D. Every time I run that compatibility command, it switches between STP and RSTP. I can’t seem to find any good documentation of this log message or this behavior. Is this potentially a firmware bug? I haven’t been notified of any issues, I just noticed it when doing some health checks on this customers network. Sorry if this is a newbie question, I am just a young and new jr network engineer with not much help.

Thanks!