I'm seeing a similar problem I did with the EAP245v3 months ago following a f/w update.  The EAP245v3 was patched to solve the problem, but the EAP225v3 was not.  With nothing else having changed, the error/drop rate is substantially higher with v5.1.0 as compared to 5.0.8.  NOTE the same problem existed with 5.0.9 as well.

From the image below you can see clearly when I updated the firmware on April 20.  I'm running Omada s/w controller 5.9.9 (linux).  I'm not experiencing any problems with connecting clients, so this could be erroneous reporting by the controller (?).  I have eight clients connecting, mostly IoT devices including power monitors and two cameras.  The errors appear to be on the 2.4ghz band (5 clients).  This may be the same problem the EAP245v3 had and was patched with a subsesquent f/w update (see ref above).  Thx.